From ZDoom Wiki
A_SkullAttack [(int speed)]
The attack of Doom's lost soul. The calling actor charges at its current target. The speed parameter defines the speed of the charge (20 by default).
This example is taken straight from Doom's Lost Soul.
Missile: SKUL C 10 bright A_FaceTarget SKUL D 4 bright A_SkullAttack SKUL CD 4 bright goto Missile+2