If your opponent plays a high-cost Character to get around "OP04-055 Plague Rounds", bust out "OP01-070 Dracule Mihawk" or "OP04-044 Kaido" to take it down
Funny as ever
Tatyova, Benthic Druid I wont pretend that Tatyova, Benthic Druid is a terribly exciting merfolk commander, but it does offer very consistent value in the form of card advantage
Darksteel Monolith Darksteel Monolith is an extremely strong card in the Eldrazi Unbound precon deck, as it allows the player to cast enormous Eldrazi cards like Kozilek the Great Distortion for free, not to mention powerful instants or sorceries like Rise of the Eldrazi
This one definitely needs to be an instant, because otherwise it would be completely useless, but at the same time, I dont think this should be a mythic
Tekuthal, Inquiry Dominus If you want a challenge, then the Mono-Blue Commander Tekuthal, Inquiry Dominus is the mechanic's most explosive payoff