, Remove a counter from a nonland permanent you control: Draw a card.
O'aka turns counters into cards: each turn you tap her, pull a counter off any nonland permanent you control, and draw. Build an engine that constantly restocks counters (proliferate, +1/+1 sources, charge counters, planeswalkers) so you always have fuel, then snowball card advantage in mono-blue and win with the resources you've stockpiled. You play a controlling, value-grindy game and bury opponents under card flow.
Repeatable card advantage on a 2-mana commander, available early and often
Deep synergy with the entire counters-matters package (proliferate, charge counters, +1/+1)
Mono-blue gives premier counterspells, card draw, and protection to keep the engine online
Cheap to recast and easy to slot into existing blue control or counters shells
Only one activation per turn unless you untap her, so raw card velocity is modest
Needs a steady counter supply or the ability simply turns off
Mono-blue struggles with permanent-based threats and broad removal
Removal-prone—opponents can kill her to stop the value, and blue can't easily rebuild board presence