Combo strategies that depend on synergy will see their win rate tank as they have to discard a card every turn, losing the chance to combo off
Its valuable too, currently selling for aound $280
That's what it comes down to
Not a great combat body, not a great blocker by any means
Along with the two starter decks, there will be a new Illumineer's Trove and new accessories like deck boxes, card sleeves, and playmats
Off the top of my head, in Standard and Modern, it prevents some or all of the use of the following cards: Every flashback card (in particular) Ancient Grudge Desperate Ravings Dread Return Dream Twist Faithless Looting Forbidden Alchemy Mystical Teachings Past in Flames Think Twice Unburial Rites Snapcaster Mage Narcomoeba Reanimate Exhume Every undying creature Every persist creature Gravecrawler Ichorid Ashen Ghoul Proclamation of Rebirth Polymorph Probably quite a few others 1) Drogskol Captain Hexproof is a very non-interactive creature mechanic, making it one of the more powerful mechanics to have been printed in recent years