I think it's a neat card, but so far I haven't seen any real strong suggestions. It's the type of card you need multiple turns to really get value off it. It's like passively drawing a second card every turn. It wins a top decking situation... maybe, because the turn you play it you've done nothing to affect the board.
It's unique and it looks fun. I'll probably craft it and try to make it work.
So far I am not seeing many combos that aren't better performed another way. Leeroy has shadowstep. Jades have shadowcaster, granted I still think this has a lot of potential with jades.
There are two unique uses I see so far. 1, it copies spells which rogue can't easily do except with rng off mimic pod. 2, arcane giants should work as arcane giant cost should be an exception to the whole "no cost reduction", cause it's not copying the cost reduction as a copied arcane giant will reduce itself.
I wish this could work with malygos somehow.