The star of GX cards is their new mechanic, GX attacks
Grist, the Hunger Tide Grist, the Hunger Tide is one of the more unique commanders on this list, as it's simultaneously a creature and and planeswalker when it isn't on the battlefield
The first time you crew it each time, you can draw two cards if it was double crewed and you smash face, I really like in in Zombie token decks since they have loads of spare 2/2 tokens running around to double crew it
He can defend himself, isnt terribly over-costed, and lets you ramp into end-game creature options
Tundra, on the other hand, enters untapped and doesnt require any additional costs to be paid
Commander is one of MTGs most popular formats, allowing groups of four players to face each other with 100-card decks and their life points increased to 40