When this card enters play, you revive a creature from either graveyard, put it under control, and give it a massive penalty of (wait for it) -1/0
Even having just one of these creatures in play lets you cast spells you wouldnt normally be able to or psyche your opponents into playing into your own counterspells while thinking you dont have the available mana open
Fake Cards Age of the Card Trading Card Game Meta Trends in the Pokemon World External Media What Impact Does Grading Have on Your Pokemon Cards
Luffy Starter Deck [ST-18], Black Smoker Starter Deck [ST-19], Yellow Charlotte Katakuri Starter Deck [ST-20] 8 November ONE PIECE CARD THE BEST Premium Booster [PRB-01] 13 December Emperors in the New World [OP-09], Double Pack Set Vol
This is why having no hand size limit is vital to ensure you won't have to discard cards out of your hand
As you can likely tell by the card, his true form turns out to be the primal Hades, and given his intense nostalgic living in the past, it makes sense that he'd have a Yawgmoth's Will-like effect