Each opponent can't cast noncreature spells with mana value greater than the number of lands that player controls.
Whenever an opponent casts a spell, if no mana was spent to cast it, counter that spell.
Lavinia is a stax/tempo commander who locks opponents out of free spells and big noncreature haymakers while you build an efficient board and grind value. You deploy early disruption, keep land counts low for opponents via taxes and denial, and close with creatures or a controlling lock. Turn to turn you're trading resources unfairly, punishing greedy mana bases and free-cast cheavy decks.
Free, body-as-commander hatebear that hard-counters cascade, free spells, and ritual-fueled cheats
Caps opponents' big noncreature plays based on their land count, neutralizing many bombs and board wipes
Cheap two-drop that pressures and disrupts simultaneously
Excellent in metas full of cEDH staples like Force of Will, Dockside, and cascade
Doesn't stop creature spells or activated/triggered abilities at all
Easily removed two-drop that opponents will prioritize killing
Symmetrical-ish strategy can leave you mana-light if you over-commit to stax
UW lacks fast ramp and big closing power without dedicated wincons