Eriette's Lullaby

In Commander, Eriette's Lullaby punches above its weight because the "each opponent" clause scales with pod size — at a four-player table you're threatening up to three sacrifices and 6 life loss off a single spell. The forced sacrifice hits planeswalkers alongside creatures, which is rarer than it looks at this mana cost and matters when your opponents are protecting a Doubling Season setup. In 1v1 formats like Modern and Pioneer it's narrower, since forcing a single sacrifice of the highest-power creature is situationally strong but competes with unconditional removal that doesn't let the opponent choose. Pauper and Legacy have enough redundant threat density that one forced sacrifice rarely closes a game on its own. Stick to Commander as the primary home.