Can I corrupt a unit as a cost (Dark Elf Mortella) while she is blocking, say to play Striking the Grudge from my opponents deck and use it on her? Or does the fact that I have just corrupted her remove her from combat?

Corruption simply prevents a unit from being declared as an attacker or defender. Once a unit has been declared attacking or defending, you can corrupt them all you want - they'll still have been declared already and will still participate in combat.

Thanx! That was my ruling too.

Do you have to pay the cost of the tactic ignioring the loyallty? I think you do but just checking!!!

badgertheking said:

For Mortella, yes you ignore loyalty costs.