I think that there are already some combos that work okay with void terror, but the problem is that if you are relying on combos then you want a bigger impact than void terror brings to make up for all the times that you only have one half of the combo. Void terror also scales bad if you go much later than turn 5, and he is weak to silence. I think it needs base stats of 3/4 or even just 2/4 to make it a good card. If you could just have it eat a 1 health minion and become a Yeti then it might be worth using in decks with abusive sergents or ironbeak owls. Another problem is that warlocks do not run loot hoarders, which currently would be one of the best cards to use void terror with.