Alchemist's Gambit

In Commander, Alchemist's Gambit is a niche extra-turn spell that earns its slot only in decks built to neutralize the delayed life-loss trigger — Obeka, Brute Chronologist shells are the clearest home. Outside of those synergy builds, it competes against cleaner options and usually loses. In competitive formats like Modern and Legacy, extra-turn spells need to either win on the spot or chain into a kill, and Alchemist's Gambit does neither reliably enough to see play. Pioneer is the same story — the format has enough pressure that a conditional extra turn at four mana rarely closes the game. Oathbreaker follows the Commander logic: worth it if your planeswalker or signature spell can exploit the additional turn before the trigger bites you.