Generate a card is not even comparable to draw a card, you are generating a random resource that somethimes isn't even useful to you unlike drawing a card that will always get take you one step closer to accomplish your game plan.

If this card get you one card from your opponent's hand then it's a terrible deal, if gets you two cards it's okay, a 4 mana 3/6 body with thoughsteal attached but the more expensive the card is the value get worse, It's only good if you are able to gain 3 cards from it, I don't think you will have the space in hand to gain more than 4 from this except in the scenarios I mentioned before, ultra late game (fatigue) even in there your opponent might have few cards, and in a Tempo archetype where you need the refill (and maybe not even a useful one)

Anyway, it's just a custom card.