Enduring Renewal + Shield Sphere + Intruder Alarm + Gríma Wormtongue

Enduring Renewal

Shield Sphere

Intruder Alarm

Gríma Wormtongue

How it works

1. Activate Grima Wormtongue by tapping it and sacrificing Shield Sphere.
2. When Shield Sphere dies, Enduring Renewal triggers, returning Shield Sphere from your graveyard to your hand.
3. Resolve the Grima Wormtongue ability, causing target player to lose 1 life.
4. Cast Shield Sphere by paying 0.
5. Repeat.

This ingenious loop relies on Enduring Renewal's static ability to bypass the normal permanence of death, automatically returning Shield Sphere to your hand the moment it hits the graveyard. Because Shield Sphere costs zero mana, you can recast it infinitely to fuel Gríma Wormtongue's sacrifice ability, which continually drains your opponents of life while bypassing their life-gain attempts. Although Intruder Alarm is along for the ride (triggering endlessly on each zero-mana creature recast), the core engine is a relentless zero-cost recursion loop that grinds down the table through sheer persistence.