How does the timing work when area-of-effect damage creates new targets?
Cards are resolved in order. So for instance in this scenario if you deal your damage you might look like this:


Gloomweaver 3 damage (Because he's the first card that came out) &lt;-- not actually true, damage is dealt in player's choice order
Environment Card (Because something has been sticking around)
Villain Card (Dead; Add Zombie)
Villain Card (3 Damage)
New Zombie (3 Damage) 


So yes you would do that damage to the zombie.