qzdoom-gpl/wadsrc/static/actors/hexen/bats.txt

// Bat Spawner --------------------------------------------------------------

ACTOR BatSpawner : SwitchableDecoration
{
	+NOBLOCKMAP +NOSECTOR +NOGRAVITY
	RenderStyle None

	action native A_BatSpawnInit();
	action native A_BatSpawn();

	States
	{
	Spawn:
	Active:
		TNT1 A 2
		TNT1 A 2 A_BatSpawnInit
		TNT1 A 2 A_BatSpawn
		Wait
	Inactive:
		TNT1 A -1
		Stop
	}
}

// Bat ----------------------------------------------------------------------

ACTOR Bat
{
	Speed 5
	Radius 3
	Height 3
	+NOBLOCKMAP +NOGRAVITY +MISSILE
	+NOTELEPORT +CANPASS

	action native A_BatMove();

	States
	{
	Spawn:
		ABAT ABC 2 A_BatMove
		Loop
	Death:
		ABAT A 2
		Stop
	}
}