Scholomance Academy Cards List & Guide
I wonder if you still get the Hero Power effect when you Invoke if there's no Galakrond in your deck.
Most Invoke cards seem to be slightly bad if you take that away. Combo decks that don't care about Galakrond might be less inclined to abuse this if they have to include too many truly bad cards.
Complaining about RNG in Hearthstone won't convince anyone that it's a bad thing -- it only makes them think you're too dimwitted to find a game that suits you better.