diff --git a/src/actor.h b/src/actor.h
index dc2ee0510..9c4fd9ff7 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -604,7 +604,7 @@ public:
 
 	// Perform some special damage action. Returns the amount of damage to do.
 	// Returning -1 signals the damage routine to exit immediately
-	virtual int DoSpecialDamage (AActor *target, int damage);
+	virtual int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 
 	// Like DoSpecialDamage, but called on the actor receiving the damage.
 	virtual int TakeSpecialDamage (AActor *inflictor, AActor *source, int damage, FName damagetype);
diff --git a/src/g_heretic/a_hereticweaps.cpp b/src/g_heretic/a_hereticweaps.cpp
index 79291659f..e8f287f69 100644
--- a/src/g_heretic/a_hereticweaps.cpp
+++ b/src/g_heretic/a_hereticweaps.cpp
@@ -335,12 +335,12 @@ class AMaceFX4 : public AActor
 {
 	DECLARE_CLASS (AMaceFX4, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (AMaceFX4)
 
-int AMaceFX4::DoSpecialDamage (AActor *target, int damage)
+int AMaceFX4::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if ((target->flags2 & MF2_BOSS) || (target->flags3 & MF3_DONTSQUASH) || target->IsTeammate (this->target))
 	{ // Don't allow cheap boss kills and don't instagib teammates
@@ -703,10 +703,10 @@ class ABlasterFX1 : public AFastProjectile
 	DECLARE_CLASS(ABlasterFX1, AFastProjectile)
 public:
 	void Effect ();
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
-int ABlasterFX1::DoSpecialDamage (AActor *target, int damage)
+int ABlasterFX1::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->IsKindOf (PClass::FindClass ("Ironlich")))
 	{ // Less damage to Ironlich bosses
@@ -736,12 +736,12 @@ class ARipper : public AActor
 {
 	DECLARE_CLASS (ARipper, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS(ARipper)
 
-int ARipper::DoSpecialDamage (AActor *target, int damage)
+int ARipper::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->IsKindOf (PClass::FindClass ("Ironlich")))
 	{ // Less damage to Ironlich bosses
@@ -822,12 +822,12 @@ class AHornRodFX2 : public AActor
 {
 	DECLARE_CLASS (AHornRodFX2, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (AHornRodFX2)
 
-int AHornRodFX2::DoSpecialDamage (AActor *target, int damage)
+int AHornRodFX2::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->IsKindOf (PClass::FindClass("Sorcerer2")) && pr_hrfx2() < 96)
 	{ // D'Sparil teleports away
@@ -843,12 +843,12 @@ class ARainPillar : public AActor
 {
 	DECLARE_CLASS (ARainPillar, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (ARainPillar)
 
-int ARainPillar::DoSpecialDamage (AActor *target, int damage)
+int ARainPillar::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->flags2 & MF2_BOSS)
 	{ // Decrease damage for bosses
@@ -1154,13 +1154,13 @@ class APhoenixFX1 : public AActor
 {
 	DECLARE_CLASS (APhoenixFX1, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 
 IMPLEMENT_CLASS (APhoenixFX1)
 
-int APhoenixFX1::DoSpecialDamage (AActor *target, int damage)
+int APhoenixFX1::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->IsKindOf (PClass::FindClass("Sorcerer2")) && pr_hrfx2() < 96)
 	{ // D'Sparil teleports away
@@ -1176,12 +1176,12 @@ class APhoenixFX2 : public AActor
 {
 	DECLARE_CLASS (APhoenixFX2, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (APhoenixFX2)
 
-int APhoenixFX2::DoSpecialDamage (AActor *target, int damage)
+int APhoenixFX2::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->player && pr_pfx2 () < 128)
 	{ // Freeze player for a bit
diff --git a/src/g_heretic/a_ironlich.cpp b/src/g_heretic/a_ironlich.cpp
index 61220f419..8efa08273 100644
--- a/src/g_heretic/a_ironlich.cpp
+++ b/src/g_heretic/a_ironlich.cpp
@@ -19,12 +19,12 @@ class AWhirlwind : public AActor
 {
 	DECLARE_CLASS (AWhirlwind, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS(AWhirlwind)
 
-int AWhirlwind::DoSpecialDamage (AActor *target, int damage)
+int AWhirlwind::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	int randVal;
 
diff --git a/src/g_hexen/a_clericstaff.cpp b/src/g_hexen/a_clericstaff.cpp
index 8dc8c0916..36f0c7686 100644
--- a/src/g_hexen/a_clericstaff.cpp
+++ b/src/g_hexen/a_clericstaff.cpp
@@ -22,12 +22,12 @@ class ACStaffMissile : public AActor
 {
 	DECLARE_CLASS (ACStaffMissile, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (ACStaffMissile)
 
-int ACStaffMissile::DoSpecialDamage (AActor *target, int damage)
+int ACStaffMissile::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	// Cleric Serpent Staff does poison damage
 	if (target->player)
diff --git a/src/g_hexen/a_fighterquietus.cpp b/src/g_hexen/a_fighterquietus.cpp
index 8bc27751c..0ba8abd6f 100644
--- a/src/g_hexen/a_fighterquietus.cpp
+++ b/src/g_hexen/a_fighterquietus.cpp
@@ -58,12 +58,12 @@ class AFSwordMissile : public AActor
 {
 	DECLARE_CLASS (AFSwordMissile, AActor)
 public:
-	int DoSpecialDamage(AActor *victim, AActor *source, int damage);
+	int DoSpecialDamage(AActor *victim, AActor *source, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (AFSwordMissile)
 
-int AFSwordMissile::DoSpecialDamage(AActor *victim, AActor *source, int damage)
+int AFSwordMissile::DoSpecialDamage(AActor *victim, AActor *source, int damage, FName damagetype)
 {
 	if (victim->player)
 	{
diff --git a/src/g_hexen/a_flechette.cpp b/src/g_hexen/a_flechette.cpp
index 779b9424c..11352a41d 100644
--- a/src/g_hexen/a_flechette.cpp
+++ b/src/g_hexen/a_flechette.cpp
@@ -307,7 +307,7 @@ class APoisonCloud : public AActor
 {
 	DECLARE_CLASS (APoisonCloud, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 	void BeginPlay ();
 };
 
@@ -320,7 +320,7 @@ void APoisonCloud::BeginPlay ()
 	special2 = 0;
 }
 
-int APoisonCloud::DoSpecialDamage (AActor *victim, int damage)
+int APoisonCloud::DoSpecialDamage (AActor *victim, int damage, FName damagetype)
 {
 	if (victim->player)
 	{
@@ -343,12 +343,18 @@ int APoisonCloud::DoSpecialDamage (AActor *victim, int damage)
 			{
 				damage = (int)((float)damage * level.teamdamage);
 			}
+			// Modify with damage factors
+			damage = FixedMul(damage, victim->DamageFactor);
+			if (damage > 0)
+			{
+				damage = DamageTypeDefinition::ApplyMobjDamageFactor(damage, damagetype, victim->GetClass()->ActorInfo->DamageFactors);
+			}
 			if (damage > 0)
 			{
 				P_PoisonDamage (victim->player, this,
 					15+(pr_poisoncloudd()&15), false); // Don't play painsound
 
-				// If successful, play the posion sound.
+				// If successful, play the poison sound.
 				if (P_PoisonPlayer (victim->player, this, this->target, 50))
 					S_Sound (victim, CHAN_VOICE, "*poison", 1, ATTN_NORM);
 			}
diff --git a/src/g_hexen/a_magecone.cpp b/src/g_hexen/a_magecone.cpp
index 84d53db56..6356fbb2f 100644
--- a/src/g_hexen/a_magecone.cpp
+++ b/src/g_hexen/a_magecone.cpp
@@ -29,12 +29,12 @@ class AFrostMissile : public AActor
 {
 	DECLARE_CLASS (AFrostMissile, AActor)
 public:
-	int DoSpecialDamage (AActor *victim, int damage);
+	int DoSpecialDamage (AActor *victim, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (AFrostMissile)
 
-int AFrostMissile::DoSpecialDamage (AActor *victim, int damage)
+int AFrostMissile::DoSpecialDamage (AActor *victim, int damage, FName damagetype)
 {
 	if (special2 > 0)
 	{
diff --git a/src/g_hexen/a_teleportother.cpp b/src/g_hexen/a_teleportother.cpp
index 8de2ab0c3..8bd17b62b 100644
--- a/src/g_hexen/a_teleportother.cpp
+++ b/src/g_hexen/a_teleportother.cpp
@@ -42,7 +42,7 @@ class ATelOtherFX1 : public AActor
 {
 	DECLARE_CLASS (ATelOtherFX1, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (ATelOtherFX1)
@@ -115,7 +115,7 @@ bool AArtiTeleportOther::Use (bool pickup)
 //
 //===========================================================================
 
-int ATelOtherFX1::DoSpecialDamage (AActor *target, int damage)
+int ATelOtherFX1::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if ((target->flags3 & MF3_ISMONSTER || target->player != NULL) &&
 		!(target->flags2 & MF2_BOSS) &&
diff --git a/src/g_raven/a_minotaur.cpp b/src/g_raven/a_minotaur.cpp
index 8565a9b2a..36a5537bc 100644
--- a/src/g_raven/a_minotaur.cpp
+++ b/src/g_raven/a_minotaur.cpp
@@ -56,9 +56,9 @@ bool AMinotaur::Slam (AActor *thing)
 	return Super::Slam (thing);
 }
 
-int AMinotaur::DoSpecialDamage (AActor *target, int damage)
+int AMinotaur::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
-	damage = Super::DoSpecialDamage (target, damage);
+	damage = Super::DoSpecialDamage (target, damage, damagetype);
 	if ((damage != -1) && (flags & MF_SKULLFLY))
 	{ // Slam only when in charge mode
 		P_MinotaurSlam (this, target);
diff --git a/src/g_raven/ravenshared.h b/src/g_raven/ravenshared.h
index 16ae44796..726dc1a38 100644
--- a/src/g_raven/ravenshared.h
+++ b/src/g_raven/ravenshared.h
@@ -7,7 +7,7 @@ class AMinotaur : public AActor
 {
 	DECLARE_CLASS (AMinotaur, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 
 public:
 	bool Slam (AActor *);
diff --git a/src/g_shared/a_morph.cpp b/src/g_shared/a_morph.cpp
index 0f51d373b..d3b8d4ac8 100644
--- a/src/g_shared/a_morph.cpp
+++ b/src/g_shared/a_morph.cpp
@@ -535,7 +535,7 @@ bool P_MorphedDeath(AActor *actor, AActor **morphed, int *morphedstyle, int *mor
 
 IMPLEMENT_CLASS(AMorphProjectile)
 
-int AMorphProjectile::DoSpecialDamage (AActor *target, int damage)
+int AMorphProjectile::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	const PClass *morph_flash = PClass::FindClass (MorphFlash);
 	const PClass *unmorph_flash = PClass::FindClass (UnMorphFlash);
diff --git a/src/g_shared/a_sharedglobal.h b/src/g_shared/a_sharedglobal.h
index 1b7521357..87e103975 100644
--- a/src/g_shared/a_sharedglobal.h
+++ b/src/g_shared/a_sharedglobal.h
@@ -156,7 +156,7 @@ class AMorphProjectile : public AActor
 {
 	DECLARE_CLASS (AMorphProjectile, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 	void Serialize (FArchive &arc);
 
 	FNameNoInit	PlayerClass, MonsterClass, MorphFlash, UnMorphFlash;
diff --git a/src/g_strife/a_loremaster.cpp b/src/g_strife/a_loremaster.cpp
index 8613aacee..3c42ea181 100644
--- a/src/g_strife/a_loremaster.cpp
+++ b/src/g_strife/a_loremaster.cpp
@@ -14,12 +14,12 @@ class ALoreShot : public AActor
 {
 	DECLARE_CLASS (ALoreShot, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (ALoreShot)
 
-int ALoreShot::DoSpecialDamage (AActor *target, int damage)
+int ALoreShot::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	FVector3 thrust;
 	
diff --git a/src/g_strife/a_strifeweapons.cpp b/src/g_strife/a_strifeweapons.cpp
index e7a9a8533..596e91e07 100644
--- a/src/g_strife/a_strifeweapons.cpp
+++ b/src/g_strife/a_strifeweapons.cpp
@@ -158,12 +158,12 @@ class APoisonBolt : public AActor
 {
 	DECLARE_CLASS (APoisonBolt, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (APoisonBolt)
 
-int APoisonBolt::DoSpecialDamage (AActor *target, int damage)
+int APoisonBolt::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->flags & MF_NOBLOOD)
 	{
@@ -551,18 +551,18 @@ class APhosphorousFire : public AActor
 {
 	DECLARE_CLASS (APhosphorousFire, AActor)
 public:
-	int DoSpecialDamage (AActor *target, int damage);
+	int DoSpecialDamage (AActor *target, int damage, FName damagetype);
 };
 
 IMPLEMENT_CLASS (APhosphorousFire)
 
-int APhosphorousFire::DoSpecialDamage (AActor *target, int damage)
+int APhosphorousFire::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->flags & MF_NOBLOOD)
 	{
 		return damage / 2;
 	}
-	return Super::DoSpecialDamage (target, damage);
+	return Super::DoSpecialDamage (target, damage, damagetype);
 }
 
 DEFINE_ACTION_FUNCTION(AActor, A_BurnArea)
diff --git a/src/p_interaction.cpp b/src/p_interaction.cpp
index 538581327..b22c60bc1 100644
--- a/src/p_interaction.cpp
+++ b/src/p_interaction.cpp
@@ -991,7 +991,7 @@ void P_DamageMobj (AActor *target, AActor *inflictor, AActor *source, int damage
 				}
 			}
 
-			damage = inflictor->DoSpecialDamage (target, damage);
+			damage = inflictor->DoSpecialDamage (target, damage, mod);
 			if (damage == -1)
 			{
 				return;
@@ -1566,6 +1566,19 @@ void P_PoisonDamage (player_t *player, AActor *source, int damage,
 		// Take half damage in trainer mode
 		damage = FixedMul(damage, G_SkillProperty(SKILLP_DamageFactor));
 	}
+	// Modify with damage factors
+	if (damage > 0)
+	{
+		damage = FixedMul(damage, target->DamageFactor);
+		if (damage > 0)
+		{
+			damage = DamageTypeDefinition::ApplyMobjDamageFactor(damage, player->poisontype, target->GetClass()->ActorInfo->DamageFactors);
+		}
+		if (damage <= 0)
+		{ // Damage was reduced to 0, so don't bother further.
+			return;
+		}
+	}
 	if (damage >= player->health
 		&& (G_SkillProperty(SKILLP_AutoUseHealth) || deathmatch)
 		&& !player->morphTics)
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 0f2a7e8ae..4f0ca0069 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -5755,7 +5755,7 @@ bool AActor::IsHostile (AActor *other)
 	return true;
 }
 
-int AActor::DoSpecialDamage (AActor *target, int damage)
+int AActor::DoSpecialDamage (AActor *target, int damage, FName damagetype)
 {
 	if (target->player && target->player->mo == target && damage < 1000 &&
 		(target->player->cheats & CF_GODMODE))