diff --git a/src/g_hexen/a_dragon.cpp b/src/g_hexen/a_dragon.cpp
deleted file mode 100644
index b79d92b36..000000000
--- a/src/g_hexen/a_dragon.cpp
+++ /dev/null
@@ -1,311 +0,0 @@
-/*
-#include "actor.h"
-#include "info.h"
-#include "p_enemy.h"
-#include "p_local.h"
-#include "a_action.h"
-#include "m_random.h"
-#include "s_sound.h"
-#include "vm.h"
-*/
-
-static FRandom pr_dragonseek ("DragonSeek");
-static FRandom pr_dragonflight ("DragonFlight");
-static FRandom pr_dragonflap ("DragonFlap");
-static FRandom pr_dragonfx2 ("DragonFX2");
-
-DECLARE_ACTION(A_DragonFlight)
-
-//============================================================================
-//
-// DragonSeek
-//
-//============================================================================
-
-static void DragonSeek (AActor *actor, DAngle thresh, DAngle turnMax)
-{
-	int dir;
-	double dist;
-	DAngle delta;
-	AActor *target;
-	int i;
-	DAngle bestAngle;
-	DAngle angleToSpot, angleToTarget;
-	AActor *mo;
-
-	target = actor->tracer;
-	if(target == NULL)
-	{
-		return;
-	}
-	dir = P_FaceMobj (actor, target, &delta);
-	if (delta > thresh)
-	{
-		delta /= 2;
-		if (delta > turnMax)
-		{
-			delta = turnMax;
-		}
-	}
-	if (dir)
-	{ // Turn clockwise
-		actor->Angles.Yaw += delta;
-	}
-	else
-	{ // Turn counter clockwise
-		actor->Angles.Yaw -= delta;
-	}
-	actor->VelFromAngle();
-
-	dist = actor->DistanceBySpeed(target, actor->Speed);
-	if (actor->Top() < target->Z() ||
-		target->Top() < actor->Z())
-	{
-		actor->Vel.Z = (target->Z() - actor->Z()) / dist;
-	}
-	if (target->flags&MF_SHOOTABLE && pr_dragonseek() < 64)
-	{ // attack the destination mobj if it's attackable
-		AActor *oldTarget;
-		
-		if (absangle(actor->Angles.Yaw, actor->AngleTo(target)) < 22.5)
-		{
-			oldTarget = actor->target;
-			actor->target = target;
-			if (actor->CheckMeleeRange ())
-			{
-				int damage = pr_dragonseek.HitDice (10);
-				int newdam = P_DamageMobj (actor->target, actor, actor, damage, NAME_Melee);
-				P_TraceBleed (newdam > 0 ? newdam : damage, actor->target, actor);
-				S_Sound (actor, CHAN_WEAPON, actor->AttackSound, 1, ATTN_NORM);
-			}
-			else if (pr_dragonseek() < 128 && P_CheckMissileRange(actor))
-			{
-				P_SpawnMissile(actor, target, PClass::FindActor("DragonFireball"));						
-				S_Sound (actor, CHAN_WEAPON, actor->AttackSound, 1, ATTN_NORM);
-			}
-			actor->target = oldTarget;
-		}
-	}
-	if (dist < 4)
-	{ // Hit the target thing
-		if (actor->target && pr_dragonseek() < 200)
-		{
-			AActor *bestActor = NULL;
-			bestAngle = 360.;
-			angleToTarget = actor->AngleTo(actor->target);
-			for (i = 0; i < 5; i++)
-			{
-				if (!target->args[i])
-				{
-					continue;
-				}
-				FActorIterator iterator (target->args[i]);
-				mo = iterator.Next ();
-				if (mo == NULL)
-				{
-					continue;
-				}
-				angleToSpot = actor->AngleTo(mo);
-				DAngle diff = absangle(angleToSpot, angleToTarget);
-				if (diff < bestAngle)
-				{
-					bestAngle = diff;
-					bestActor = mo;
-				}
-			}
-			if (bestActor != NULL)
-			{
-				actor->tracer = bestActor;
-			}
-		}
-		else
-		{
-			// [RH] Don't lock up if the dragon doesn't have any
-			// targets defined
-			for (i = 0; i < 5; ++i)
-			{
-				if (target->args[i] != 0)
-				{
-					break;
-				}
-			}
-			if (i < 5)
-			{
-				do
-				{
-					i = (pr_dragonseek()>>2)%5;
-				} while(!target->args[i]);
-				FActorIterator iterator (target->args[i]);
-				actor->tracer = iterator.Next ();
-			}
-		}
-	}
-}
-
-//============================================================================
-//
-// A_DragonInitFlight
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonInitFlight)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	FActorIterator iterator (self->tid);
-
-	do
-	{ // find the first tid identical to the dragon's tid
-		self->tracer = iterator.Next ();
-		if (self->tracer == NULL)
-		{
-			self->SetState (self->SpawnState);
-			return 0;
-		}
-	} while (self->tracer == self);
-	self->RemoveFromHash ();
-	return 0;
-}
-
-//============================================================================
-//
-// A_DragonFlight
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonFlight)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	DAngle angle;
-
-	DragonSeek (self, 4., 8.);
-	if (self->target)
-	{
-		if(!(self->target->flags&MF_SHOOTABLE))
-		{ // target died
-			self->target = NULL;
-			return 0;
-		}
-		angle = absangle(self->Angles.Yaw, self->AngleTo(self->target));
-		if (angle <22.5 && self->CheckMeleeRange())
-		{
-			int damage = pr_dragonflight.HitDice (8);
-			int newdam = P_DamageMobj (self->target, self, self, damage, NAME_Melee);
-			P_TraceBleed (newdam > 0 ? newdam : damage, self->target, self);
-			S_Sound (self, CHAN_WEAPON, self->AttackSound, 1, ATTN_NORM);
-		}
-		else if (angle <= 20)
-		{
-			self->SetState (self->MissileState);
-			S_Sound (self, CHAN_WEAPON, self->AttackSound, 1, ATTN_NORM);
-		}
-	}
-	else
-	{
-		P_LookForPlayers (self, true, NULL);
-	}
-	return 0;
-}
-
-//============================================================================
-//
-// A_DragonFlap
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonFlap)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	CALL_ACTION(A_DragonFlight, self);
-	if (pr_dragonflap() < 240)
-	{
-		S_Sound (self, CHAN_BODY, "DragonWingflap", 1, ATTN_NORM);
-	}
-	else
-	{
-		self->PlayActiveSound ();
-	}
-	return 0;
-}
-
-//============================================================================
-//
-// A_DragonAttack
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonAttack)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	P_SpawnMissile (self, self->target, PClass::FindActor("DragonFireball"));
-	return 0;
-}
-
-//============================================================================
-//
-// A_DragonFX2
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonFX2)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	AActor *mo;
-	int i;
-	int delay;
-
-	delay = 16+(pr_dragonfx2()>>3);
-	for (i = 1+(pr_dragonfx2()&3); i; i--)
-	{
-		double xo = (pr_dragonfx2() - 128) / 4.;
-		double yo = (pr_dragonfx2() - 128) / 4.;
-		double zo = (pr_dragonfx2() - 128) / 16.;
-
-		mo = Spawn ("DragonExplosion", self->Vec3Offset(xo, yo, zo), ALLOW_REPLACE);
-		if (mo)
-		{
-			mo->tics = delay+(pr_dragonfx2()&3)*i*2;
-			mo->target = self->target;
-		}
-	}
-	return 0;
-}
-
-//============================================================================
-//
-// A_DragonPain
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonPain)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	CALL_ACTION(A_Pain, self);
-	if (!self->tracer)
-	{ // no destination spot yet
-		self->SetState (self->SeeState);
-	}
-	return 0;
-}
-
-//============================================================================
-//
-// A_DragonCheckCrash
-//
-//============================================================================
-
-DEFINE_ACTION_FUNCTION(AActor, A_DragonCheckCrash)
-{
-	PARAM_SELF_PROLOGUE(AActor);
-
-	if (self->Z() <= self->floorz)
-	{
-		self->SetState (self->FindState ("Crash"));
-	}
-	return 0;
-}
diff --git a/src/g_hexen/a_hexenmisc.cpp b/src/g_hexen/a_hexenmisc.cpp
index 1a635ff71..f1f4a86fe 100644
--- a/src/g_hexen/a_hexenmisc.cpp
+++ b/src/g_hexen/a_hexenmisc.cpp
@@ -33,7 +33,6 @@
 #include "a_clericholy.cpp"
 #include "a_clericmace.cpp"
 #include "a_clericstaff.cpp"
-#include "a_dragon.cpp"
 #include "a_fighteraxe.cpp"
 #include "a_fighterhammer.cpp"
 #include "a_fighterplayer.cpp"
diff --git a/src/scripting/codegeneration/codegen.cpp b/src/scripting/codegeneration/codegen.cpp
index e33986550..44d7cda88 100644
--- a/src/scripting/codegeneration/codegen.cpp
+++ b/src/scripting/codegeneration/codegen.cpp
@@ -1670,19 +1670,23 @@ ExpEmit FxMinusSign::Emit(VMFunctionBuilder *build)
 {
 	assert(ValueType == Operand->ValueType);
 	ExpEmit from = Operand->Emit(build);
+	ExpEmit to;
 	assert(from.Konst == 0);
 	assert(ValueType->GetRegCount() == from.RegCount);
 	// Do it in-place, unless a local variable
 	if (from.Fixed)
 	{
-		ExpEmit to = ExpEmit(build, from.RegType, from.RegCount);
-		build->Emit(Operand->ValueType->GetMoveOp(), to.RegNum, from.RegNum);
-		from = to;
+		to = ExpEmit(build, from.RegType, from.RegCount);
+		from.Free(build);
+	}
+	else
+	{
+		to = from;
 	}
 
 	if (ValueType->GetRegType() == REGT_INT)
 	{
-		build->Emit(OP_NEG, from.RegNum, from.RegNum, 0);
+		build->Emit(OP_NEG, to.RegNum, from.RegNum, 0);
 	}
 	else
 	{
@@ -1690,20 +1694,20 @@ ExpEmit FxMinusSign::Emit(VMFunctionBuilder *build)
 		switch (from.RegCount)
 		{
 		case 1:
-			build->Emit(OP_FLOP, from.RegNum, from.RegNum, FLOP_NEG);
+			build->Emit(OP_FLOP, to.RegNum, from.RegNum, FLOP_NEG);
 			break;
 
 		case 2:
-			build->Emit(OP_NEGV2, from.RegNum, from.RegNum);
+			build->Emit(OP_NEGV2, to.RegNum, from.RegNum);
 			break;
 
 		case 3:
-			build->Emit(OP_NEGV3, from.RegNum, from.RegNum);
+			build->Emit(OP_NEGV3, to.RegNum, from.RegNum);
 			break;
 
 		}
 	}
-	return from;
+	return to;
 }
 
 //==========================================================================
@@ -4255,19 +4259,31 @@ FxExpression *FxAbs::Resolve(FCompileContext &ctx)
 
 ExpEmit FxAbs::Emit(VMFunctionBuilder *build)
 {
-	ExpEmit absofsteal = val->Emit(build);
-	assert(!absofsteal.Konst);
-	ExpEmit out(build, absofsteal.RegType);
-	if (absofsteal.RegType == REGT_INT)
+	assert(ValueType == val->ValueType);
+	ExpEmit from = val->Emit(build);
+	ExpEmit to;
+	assert(from.Konst == 0);
+	assert(ValueType->GetRegCount() == 1);
+	// Do it in-place, unless a local variable
+	if (from.Fixed)
 	{
-		build->Emit(OP_ABS, out.RegNum, absofsteal.RegNum, 0);
+		to = ExpEmit(build, from.RegType);
+		from.Free(build);
 	}
 	else
 	{
-		assert(absofsteal.RegType == REGT_FLOAT);
-		build->Emit(OP_FLOP, out.RegNum, absofsteal.RegNum, FLOP_ABS);
+		to = from;
 	}
-	return out;
+
+	if (ValueType->GetRegType() == REGT_INT)
+	{
+		build->Emit(OP_ABS, to.RegNum, from.RegNum, 0);
+	}
+	else
+	{
+		build->Emit(OP_FLOP, to.RegNum, from.RegNum, FLOP_ABS);
+	}
+	return to;
 }
 
 //==========================================================================
@@ -5898,6 +5914,7 @@ ExpEmit FxArrayElement::Emit(VMFunctionBuilder *build)
 	else
 	{
 		ExpEmit indexv(index->Emit(build));
+		ExpEmit indexwork = indexv.Fixed ? ExpEmit(build, indexv.RegType) : indexv;
 		int shiftbits = 0;
 		while (1u << shiftbits < arraytype->ElementSize)
 		{ 
@@ -5907,19 +5924,19 @@ ExpEmit FxArrayElement::Emit(VMFunctionBuilder *build)
 		build->Emit(OP_BOUND, indexv.RegNum, arraytype->ElementCount);
 		if (shiftbits > 0)
 		{
-			build->Emit(OP_SLL_RI, indexv.RegNum, indexv.RegNum, shiftbits);
+			build->Emit(OP_SLL_RI, indexwork.RegNum, indexv.RegNum, shiftbits);
 		}
 
 		if (AddressRequested)
 		{
-			build->Emit(OP_ADDA_RR, start.RegNum, start.RegNum, indexv.RegNum);
+			build->Emit(OP_ADDA_RR, start.RegNum, start.RegNum, indexwork.RegNum);
 		}
 		else
 		{
 			build->Emit(arraytype->ElementType->GetLoadOp() + 1,	// added 1 to use the *_R version that
-				dest.RegNum, start.RegNum, indexv.RegNum);			// takes the offset from a register
+				dest.RegNum, start.RegNum, indexwork.RegNum);			// takes the offset from a register
 		}
-		indexv.Free(build);
+		indexwork.Free(build);
 	}
 	if (AddressRequested)
 	{
@@ -6955,13 +6972,26 @@ FxExpression *FxFlopFunctionCall::Resolve(FCompileContext& ctx)
 
 ExpEmit FxFlopFunctionCall::Emit(VMFunctionBuilder *build)
 {
-	ExpEmit v = ArgList[0]->Emit(build);
-	assert(!v.Konst && v.RegType == REGT_FLOAT);
+	assert(ValueType == ArgList[0]->ValueType);
+	ExpEmit from = ArgList[0]->Emit(build);
+	ExpEmit to;
+	assert(from.Konst == 0);
+	assert(ValueType->GetRegCount() == 1);
+	// Do it in-place, unless a local variable
+	if (from.Fixed)
+	{
+		to = ExpEmit(build, from.RegType);
+		from.Free(build);
+	}
+	else
+	{
+		to = from;
+	}
 
-	build->Emit(OP_FLOP, v.RegNum, v.RegNum, FxFlops[Index].Flop);
+	build->Emit(OP_FLOP, to.RegNum, from.RegNum, FxFlops[Index].Flop);
 	ArgList.Clear();
 	ArgList.ShrinkToFit();
-	return v;
+	return to;
 }
 
 
diff --git a/src/scripting/vm/vmexec.h b/src/scripting/vm/vmexec.h
index 02e0db3de..fcdb2eb8b 100644
--- a/src/scripting/vm/vmexec.h
+++ b/src/scripting/vm/vmexec.h
@@ -696,6 +696,8 @@ begin:
 	OP(BOUND):
 		if (reg.d[a] >= BC)
 		{
+			assert(false);
+			Printf("Array access out of bounds: Max. index = %u, current index = %u\n", BC, reg.d[a]);
 			THROW(X_ARRAY_OUT_OF_BOUNDS);
 		}
 		NEXTOP;
diff --git a/wadsrc/static/zscript/hexen/dragon.txt b/wadsrc/static/zscript/hexen/dragon.txt
index 6df3da943..ed6e86d4a 100644
--- a/wadsrc/static/zscript/hexen/dragon.txt
+++ b/wadsrc/static/zscript/hexen/dragon.txt
@@ -1,6 +1,4 @@
-
 // Dragon -------------------------------------------------------------------
-
 class Dragon : Actor
 {
 	Default
@@ -23,13 +21,6 @@ class Dragon : Actor
 		Obituary "$OB_DRAGON";
 	}
 
-	native void A_DragonInitFlight();
-	native void A_DragonFlap();
-	native void A_DragonFlight();
-	native void A_DragonPain();
-	native void A_DragonAttack();
-	native void A_DragonCheckCrash();
-
 	States
 	{
 	Spawn:
@@ -58,6 +49,253 @@ class Dragon : Actor
 		DRAG M -1;
 		Stop;
 	}
+	
+	//============================================================================
+	//
+	// DragonSeek
+	//
+	//============================================================================
+
+	private void DragonSeek (double thresh, double turnMax)
+	{
+		double dist;
+		double delta;
+		Actor targ;
+		int i;
+		double bestAngle;
+		double angleToSpot, angleToTarget;
+		Actor mo;
+
+		targ = tracer;
+		if(targ == null)
+		{
+			return;
+		}
+
+		double diff = deltaangle(angle, AngleTo(targ));
+		delta = abs(diff);
+
+		if (delta > thresh)
+		{
+			delta /= 2;
+			if (delta > turnMax)
+			{
+				delta = turnMax;
+			}
+		}
+		if (diff > 0)
+		{ // Turn clockwise
+			angle = angle + delta;
+		}
+		else
+		{ // Turn counter clockwise
+			angle = angle - delta;
+		}
+		VelFromAngle();
+
+		dist = DistanceBySpeed(targ, Speed);
+		if (pos.z + height < targ.pos.z || targ.pos.z + targ.height < pos.z)
+		{
+			Vel.Z = (targ.pos.z - pos.z) / dist;
+		}
+		if (targ.bShootable && random[DragonSeek]() < 64)
+		{ // attack the destination mobj if it's attackable
+			Actor oldTarget;
+			
+			if (absangle(angle, AngleTo(targ)) < 22.5)
+			{
+				oldTarget = target;
+				target = targ;
+				if (CheckMeleeRange ())
+				{
+					int damage = random[DragonSeek](1, 8) * 10;
+					int newdam = target.DamageMobj (self, self, damage, 'Melee');
+					target.TraceBleed (newdam > 0 ? newdam : damage, self);
+					A_PlaySound (AttackSound, CHAN_WEAPON);
+				}
+				else if (random[DragonSeek]() < 128 && CheckMissileRange())
+				{
+					SpawnMissile(targ, "DragonFireball");		
+					A_PlaySound (AttackSound, CHAN_WEAPON);
+				}
+				target = oldTarget;
+			}
+		}
+		if (dist < 4)
+		{ // Hit the target thing
+			if (target && random[DragonSeek]() < 200)
+			{
+				Actor bestActor = null;
+				bestAngle = 360.;
+				angleToTarget = AngleTo(target);
+				for (i = 0; i < 5; i++)
+				{
+					if (!targ.args[i])
+					{
+						continue;
+					}
+					ActorIterator iter = ActorIterator.Create(targ.args[i]);
+					mo = iter.Next ();
+					if (mo == null)
+					{
+						continue;
+					}
+					angleToSpot = AngleTo(mo);
+					double diff = absangle(angleToSpot, angleToTarget);
+					if (diff < bestAngle)
+					{
+						bestAngle = diff;
+						bestActor = mo;
+					}
+				}
+				if (bestActor != null)
+				{
+					tracer = bestActor;
+				}
+			}
+			else
+			{
+				// [RH] Don't lock up if the dragon doesn't have any
+				// targs defined
+				for (i = 0; i < 5; ++i)
+				{
+					if (targ.args[i] != 0)
+					{
+						break;
+					}
+				}
+				if (i < 5)
+				{
+					do
+					{
+						i = (random[DragonSeek]() >> 2) % 5;
+					} while(!targ.args[i]);
+					ActorIterator iter = ActorIterator.Create(targ.args[i]);
+					tracer = iter.Next ();
+				}
+			}
+		}
+	}
+
+	//============================================================================
+	//
+	// A_DragonInitFlight
+	//
+	//============================================================================
+
+	void A_DragonInitFlight()
+	{
+		ActorIterator iter = ActorIterator.Create(tid);
+
+		do
+		{ // find the first tid identical to the dragon's tid
+			tracer = iter.Next ();
+			if (tracer == null)
+			{
+				SetState (SpawnState);
+				return;
+			}
+		} while (tracer == self);
+		RemoveFromHash ();
+	}
+
+	//============================================================================
+	//
+	// A_DragonFlight
+	//
+	//============================================================================
+
+	void A_DragonFlight()
+	{
+		double ang;
+
+		DragonSeek (4., 8.);
+		if (target)
+		{
+			if(!target.bShootable)
+			{ // target died
+				target = null;
+				return;
+			}
+			ang = absangle(angle, AngleTo(target));
+			if (ang <22.5 && CheckMeleeRange())
+			{
+				int damage = random[DragonFlight](1, 8) * 8;
+				int newdam = target.DamageMobj (self, self, damage, 'Melee');
+				target.TraceBleed (newdam > 0 ? newdam : damage, self);
+				A_PlaySound (AttackSound, CHAN_WEAPON);
+			}
+			else if (ang <= 20)
+			{
+				SetState (MissileState);
+				A_PlaySound (AttackSound, CHAN_WEAPON);
+			}
+		}
+		else
+		{
+			LookForPlayers (true);
+		}
+	}
+
+	//============================================================================
+	//
+	// A_DragonFlap
+	//
+	//============================================================================
+
+	void A_DragonFlap()
+	{
+		A_DragonFlight();
+		if (random[DragonFlight]() < 240)
+		{
+			A_PlaySound ("DragonWingflap", CHAN_BODY);
+		}
+		else
+		{
+			PlayActiveSound ();
+		}
+	}
+
+	//============================================================================
+	//
+	// A_DragonAttack
+	//
+	//============================================================================
+
+	void A_DragonAttack()
+	{
+		SpawnMissile (target, "DragonFireball");
+	}
+
+
+	//============================================================================
+	//
+	// A_DragonPain
+	//
+	//============================================================================
+
+	void A_DragonPain()
+	{
+		A_Pain();
+		if (!tracer)
+		{ // no destination spot yet
+			SetState (SeeState);
+		}
+	}
+
+	//============================================================================
+	//
+	// A_DragonCheckCrash
+	//
+	//============================================================================
+
+	void A_DragonCheckCrash()
+	{
+		if (pos.z < floorz)
+		{
+			SetStateLabel ("Crash");
+		}
+	}
 }
 
 // Dragon Fireball ----------------------------------------------------------
@@ -77,8 +315,6 @@ class DragonFireball : Actor
 		DeathSound "DragonFireballExplode";
 	}
 
-	native void A_DragonFX2();
-
 	States
 	{
 	Spawn:
@@ -90,6 +326,30 @@ class DragonFireball : Actor
 		DRFX KL 3 Bright;
 		Stop;
 	}
+	
+	//============================================================================
+	//
+	// A_DragonFX2
+	//
+	//============================================================================
+
+	void A_DragonFX2()
+	{
+		int delay = 16+(random[DragonFX2]()>>3);
+		for (int i = random[DragonFX2](1, 4); i; i--)
+		{
+			double xo = (random[DragonFX2]() - 128) / 4.;
+			double yo = (random[DragonFX2]() - 128) / 4.;
+			double zo = (random[DragonFX2]() - 128) / 16.;
+
+			Actor mo = Spawn ("DragonExplosion", Vec3Offset(xo, yo, zo), ALLOW_REPLACE);
+			if (mo)
+			{
+				mo.tics = delay + (random[DragonFX2](0, 3)) * i*2;
+				mo.target = target;
+			}
+		}
+	}
 }
 
 // Dragon Fireball Secondary Explosion --------------------------------------