Ezuri, Stalker of Spheres adds value to each proliferate card you play, and it can also help you proliferate when it enters the battlefield
They have flexible effects that I like having access to in a deck like Jeskai
We're also tweaking the removal with the addition of Crib Swap, which counts as a Knight card so it's relevant for a couple things most notably Haakon, Stromgald Scourge, which we can repeatedly recast from the graveyard
It works well with artifact reanimation effects to loop powerful ETBs like Portal to Phyrexia
Follow that with the much-dreaded annihilator ability that makes opponents sacrifice permanents whenever it attacks, indestructible, and the possibility to shuffle your entire graveyard into your deck when it dies
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