Wut. It’s an EXTREMELY overpowered card. Your hand may remain with 9 extremely overpowered cards; some of them spam Legendaries or other cards; if you are at round 10 this is extremely possible (especially for 30-card decks (e.g. the current warrior deck that is a meme routinely has the cards it needs in the end (because it’s just …the end and most cards have gone through their hand anyway))).
[and yes someone mentioned: you can even add cards to your deck potentially: makes it even easier to work]
[the worst thing you can say against it: it depends on the rest of the cards if they can do it(but if they can…)]