The replacement effect from Agate Assault's first mode will exile the target creature if it would die this turn for any reason, not just due to lethal damage
Tribute Mage, Fabricate, and, appropriately, Gamble become must-plays when your deck's in need of the Thumb
(Choose a creature with the least toughness among creatures you control and put three +1/+1 counters on it.) Whenever chaos ensues, choose up to one target creature you control and up to one target creature an opponent controls
If you're playing a commander such as Prosper, Tome-Bound or Eruth, Tormented Prophet, it won't even be hard to just cast this from exile for 3 mana
Let me ask you this - would you consider these two cards to be the same card, or different cards
So how did I do