All it takes is an assassinate/hex/sheep/shadow word death and the opponent is effectively 2 cards above you with one move (the two the void terror ate and the void terror itself gone) and those cards are in NEARLY EVERY deck in x2. My suggestion is to make the void terror immune to targetable spells (like the faerie dragon). It can still be taken down by indirect methods such as deadly shot/cc and this way it doesnt open you up for literally being 2-3 cards down in a turn.
Forget everything else with warlock right now being OP yadda yadda, I seriously just care about seeing this card being actually useful for once.
EDIT: Yes I know this belongs in Suggestions but I want to get the input of the community first.