Reaping Willow + Phyrexian Altar + Training Grounds + Defiant Greatmaw

Reaping Willow

Phyrexian Altar

Training Grounds

Defiant Greatmaw

How it works

1. Activate Reaping Willow by paying W/B due to Training Grounds and removing two counters from it, returning Defiant Greatmaw from your graveyard to the battlefield.
2. When Defiant Greatmaw enters, it triggers, putting two -1/-1 counters on Reaping Willow.
3. Activate Phyrexian Altar by sacrificing Defiant Greatmaw, adding W/B.
4. Repeat.

This elegant loop harnesses Training Grounds to slash Reaping Willow’s resurrection ability down to just one mana of any color, allowing you to continually pull Defiant Greatmaw right back out of the graveyard. When Defiant Greatmaw enters the battlefield, its triggered ability immediately drops two -1/-1 counters back onto Reaping Willow, perfectly replenishing the exact fuel Reaping Willow needs for its next activation. You then feed Defiant Greatmaw to Phyrexian Altar to generate the exact mana required to repeat the cycle, yielding an infinite stream of sacrifice and entry triggers.