Umbral Mantle + Task Force + Worthy Cause

Umbral Mantle

Task Force

Worthy Cause

How it works

1. Activate Umbral Mantle's equip ability by paying 0, targeting Task Force.
2. Task Force triggers, giving itself +0/+3 until end of turn.
3. Resolve the Umbral Mantle ability, attaching it to Task Force.
4. Repeat from step 1 an arbitrarily large number of times.
5. Cast Worthy Cause by paying and by sacrificing Task Force, causing you to gain life equal to Task Force's toughness.