ZDoom

Okay, I fixed it by giving the Puffy actor 0 damage. I wonder if Raven meant for you to take damage when walking through the aftermath of the fireball, since they made it a missile with 2 damage (even though it doesn't move anywhere)?

I have also noticed that this same fix affects the mage's lightning weapon. It does a bit of damage on the secondary spark after the lightning has stopped. Unfortunately, it also damages you, and not just the enemies.

	// [RH] Missiles moving perfectly vertical need some X/Y movement, or they
	// won't hurt anything.
	if ((flags & MF_MISSILE) && (momx|momy) == 0)
	{
		momx = 1;
	}

The trail shouldn't move and hence shouldn't do any damage. Its damage property is probably just a leftover from early development and should be set to 0.

And here's the problem:

[code] // [RH] Missiles moving perfectly vertical need some X/Y movement, or they
// won't hurt anything.
if ((flags & MF_MISSILE) && (momx|momy) == 0)
{
momx = 1;
}
[/code]

This code in AActor::Tick automatically gives a projectile some momentum so that collision checks are performed for missiles that are moving only vertically. Needless to say, it should not do that for any object that doesn't move at all! (Yes, it's a recent fix for a well known problem!)

I do believe the fireball did do some damage, though I may be mistaken.

The trail should not hurt the weredragon though.

The Weredragon's fireball trail never did damage in the original Heretic. (at least I don't think it did, it's been so long since I've played the original versions... since ZDoom supported all games)

This trail is damaging the Weredragon, and it is killing itself in around 15-20 shots.