I try to think positive about this guy. So far...
Some combinations that work for me is to use Spirit of the Bat + Rafaam's Scheme + Some sort of sacrifice card, Void Terror or EVIL Genius. If I had Rat Catcher I think it would be an awesome addition.
Also the lackey that evolves your minion up by (1) could be used on one of the Hi'reek copies.
Arena Fanatic gives some mild success to buffing Hi'reek. Doubling Imp works well in here too.
I'm no Pro but I gots a 20% win ratio *flex* rank 20 forever