Tezzeret, Agent of Bolas

In Commander, Tezzeret, Agent of Bolas is a staple in any blue-black artifact deck — the -1 tutors at instant-speed equivalent value for a planeswalker ability, and the ultimate is a realistic one-shot kill in a shell with ten or more artifacts. Legacy and Vintage see occasional fringe play in artifact-based control shells, though four mana is a steep ask in formats where games end by turn three; he shows up in slower fair builds rather than combo engines. Modern is largely the same story — playable in artifact midrange but never a format pillar. Oathbreaker is where Tezzeret, Agent of Bolas arguably does his best work outside Commander, since he can serve as the planeswalker commander himself, making the -1 a repeatable tutor engine from the command zone.