mtg cards that give you extra turns card can chain forever doubles in price Extra Turns in Commander: Solitaire

Sen Triplets is specific in the decks that can play it, but being able to ensure someone that can interact with you can't makes it a worthwhile inclusion outside of the command zone

Tannuk, Steadfast Second If haste wins games, Tannuk, Steadfast Second ensures you're already across the finish line

Sacrifice a food, they lose a life, make a ballistic boulder with the Mordor Trebuchet, they lose a life, and so on

Upon entering the battlefield, its controller has the option of having it fight a creature, making it effectively function as removal, or it can enter with twice the number of +1/+1 counters, making it a flexible hydra that can supply a great deal of value