mewtwo pokemon card brilliant stars - 056/172 - Pokémon end display Mewtwo brilliant stars stamped :

Once Cindering Cutthroat has been blocked by a single creature, activating its last ability won't cause it to become unblocked

So, rather than trying to attack with our massive amass token or worrying that our opponent will kill it with removal or a wrath, we can immediately just throw it at our opponent's face to deal an excessively lethal amount of damage

In fact, I distinctly remember during the first year of playing the game, my sibling and I acquired a pair of 1999 Worlds decks (Kai Budde and Mark Le Pine) and saw four copies of this in the sideboard of Le Pine's list

Particularly in Commander, where the high bar set for aggro decks all but demands some kind of rapid multiplicative damage scaling, having all your creatures buff each other (for free!) is a true difference-maker