Game Knights Live is a common Plane — MagicCon card from Black Lotus Unknown Planechase (PUNK), collector number PLA039.
Whenever a player casts their commander or attacks with their commander, they may say "Only one may stand." If they do, that commander becomes a Knight in addition to its other types until a player planeswalks away from Game Knights Live. Knights you control have double strike and trample. Whenever chaos ensues, commanders you control can't be blocked this turn and gain "Whenever this creature deals combat damage to a player, draw a card" until end of turn.