Ambush (When you cast this spell, reveals cards from the top of your library until you reveal a creature. Put the rest of the cards revealed this way on the bottom of your library in a random order)
Deal damage equal to the revealed creature's power to target creature. Then, put the revealed creature into your graveyard.
You could make ambush a keyword action for some flexibility:
> "Ambush. This spell deals damage equal to the revealed creature's power to target creature. (To ambush, reveal cards etc.)"
It seems weird to have ambush do all what it does and then put the creature card somewhere else instead the top of the library, especially since you just could... not do that. I'd skip that last line of text.
That does look significantly nice. The reason I put the creature into the graveyard here was it felt that the creature was being used for the ambush, and after serving that purpose of use should go to the graveyard. I will probably use this mechanic in the future, and definitely change it to a keyword action then.