Luchuirp: I have fireball throwing workers !

[Neomega]

and gives no xp to the enemy.

YOu sure about that? I could have sworn in my earlier games, when I didn't know any better, I saw ships promoting after hurling arcane barge fireballs at them, but not taking them out.

 

[hbar]

Yeah, units get XP for surviving a fireball. Trick is to not let them survive.