It's a winning condition on a five mana 2/4 body
The attack continues (Yugi: 2000 1900)
By giving one face-up Normal Monster of your choosing to your opponent, you force them to do the same with one of their Monster cards
It can search out any pendulumgraph card in the game when destroyed, and there's plenty of solid options, though tragically the best option is still banned
Celestine does require you to gain life before you can start bringing creatures back, with so many ways to efficiently gain life in Commander this isnt a problem at all
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