Sacrificing a bunch of tokens to give a huge power boost to a single creature opens up a new axis of attack especially in token decks
Thanks to Wizards for the awesome preview card
If a permanent enters the battlefield under an opponent's control with hexproof, indestructible, protection, shroud, and/or ward after Shay Cormac's first ability resolves, it won't lose that ability until you activate Shay Cormac's first ability again
Seeing as Cube is an amalgamation of some of the best cards in MTG, you can draft some combinations like this that'll win most games straight away: Doomsday + Thassa's Oracle: Get rid of your deck and you win
Furious Reprisal is a Sorcery-speed spell that costs three generic and one Red mana to cast, and deals two damage to each of two target creatures and/or players
Milling five for two mana is roughly the same as a two-damage, two-mana Lava Spike, which is far below the curve