Whenever a creature an opponent controls becomes tapped, if it isn't being declared as an attacker, put a +1/+1 counter on Rhoda.
Rhoda is a mono-white counters-matter commander that grows every time an opponent's creature is tapped outside of combat. You flood the board with tappers, detain effects, and pacifism-style tap-down to both neutralize the table's threats and balloon Rhoda into a vigilant beater. Win by either swinging with a counter-pumped Rhoda or by going wide and overrunning while the opponents' creatures sit tapped down.
Vigilance plus self-growth lets Rhoda attack and still tap-down on defense
Tapping opponents' creatures doubles as removal-light control and a counter engine
Mono-white keeps the manabase consistent and enables cheap, focused builds
Partner access to Timin gives a second commander/card-advantage option from the command zone
Mono-white struggles for card draw and ramp compared to other colors
Rhoda's growth depends on opponents having creatures to tap—weak vs. spell/artifact decks
Voltron lines fold to a single removal spell since the counters live on the commander
Tap-down doesn't stop activated abilities, ETBs, or already-resolved threats
Slow to close games if you can't assemble anchor or anthem payoffs