Whenever you gain life, put a +1/+1 counter on each Cleric you control.
Minwu turns every lifegain trigger into a board-wide pump for your Clerics, snowballing a wide army into lethal attackers. Curve out cheap Clerics, deploy life-gain enablers, then attack with vigilance/lifelink to gain even more life and grow everything further. You close games by overwhelming the table with oversized creatures or breaking symmetry with anthem and lifegain payoffs.
Mono-white tribal payoff that snowballs hard once lifegain triggers stack
Vigilance plus lifelink lets Minwu attack and still gain life to grow your board
Resilient go-wide plan that punishes slow or removal-light tables
Lifegain provides a buffer against aggro and burn
Single color means weak interaction, no card draw outside white's limited options
Board wipes reset the whole counter-stacked army at once
Mono-white ramp is poor, so big lifegain engines can come down slow
Relies on Minwu staying alive to convert lifegain into counters
Counters can be removed and the deck folds without a wide Cleric base