Think Xavier's mutant academy versus Magneto's brotherhood, Battle of Wakanda, Black Panther versus Killmonger, and Loki versus Dr
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases (such as the commander tax), then apply any cost reductions (such as that of Karador)
Mostly used in Legacy, Vintage, and Commander, this spell counters an instant or sorcery unless its controller pays , and while that seems minimal, storm turns that tax into a massive stack of headaches
Thought Monitor Thought Monitor is Mulldrifter, but potentially cheaper
The Grixis (blue/black/red) The Ruinous Powers