I agree with the Blessings of Tzeentch issue - it needs errata if it's going to do what it seems to be trying to do, i.e. a random polymorphing effect. After the Dwarven Cannon Crew ruling, you can just choose to only find the 1 creature you want.
Current card text:
Spell. ACTION: Sacrifice a unit. If you do, you may search the top 5 cards of your deck for any number of units and put one of them into play t random (you choose which zone). Then, shuffle the other cards back into your deck.
Suggested errata'd text:
Spell. ACTION: Sacrifice a unit. If you do, you may reveal the top 5 cards of your deck. Choose one revealed unit at random and put that unit into play (you choose which zone). Then, shuffle the other cards back into your deck.
Now, I think the card is just fine from the power level perspective even if it isn't random. But given that the random word is there, it seems like this is what they wanted the card to do.