Either the player can have their life points go to zero, they have no cards when its their turn to draw, or the opponent has a specific card with a condition that, if met, wins them the game
A lot of favorite legends are presumed dead
That said, a Sultai commander has the best color identity to support both poison counters and infect creatures, and Xavier is one of the very few populate commanders in Magic
Cards like Displacer Kitten, Essence Flux, and Ghostly Flicker play nicely with commanders that have enters abilities like Kefka, Court Mage and Plagon, Lord of the Beach and with common support pieces like Inalla, Archmage Ritualist and Archaeomancer
When they finish, play passes to the second player
It's none other than Morph from Treasure Planet at his absolute shiniest