When Byrke enters, put a +1/+1 counter on each of up to two target creatures.
Whenever a creature you control with a +1/+1 counter on it attacks, double the number of +1/+1 counters on it.
Byrke is a +1/+1 counters payoff that snowballs your board to lethal sizes fast. Seed counters early, then attack to double them—turning modest creatures into game-enders within a turn or two. You win by attacking with enormous trampling or evasive threats, or by going wide with counter synergies.
Exponential counter doubling creates absurd power levels by turn 6-7
GW has the best counter support, ramp, and protection in the format
Vigilance lets Byrke and counter-creatures attack without dropping defense
Resilient to spot removal since multiple creatures can carry the doubling threat
Doubling does nothing without evasion—blockers and chump blocks stall you
Relies on creatures sticking; board wipes hit very hard
Six-mana commander that's slow to come online without ramp
No card advantage or interaction baked into the commander