Yeah I like the explosive idea, it should do damage and it can be like an AoE, base it off war stomp and then make a trigger like
Events:
A unit casts a spell
Conditions:
[Casted spell] equal to [Suicidal Boom]
Actions:
Set [triggering unit] hitpoints to [-100]
or whatever, bend to your will
Sorry guys I'm back, SeRv, get on WarCraft, I'll be in USEast in channel GTF.