Szarel, Genesis Shepherd + Cauldron of Souls + Clock of Omens + Atog

Szarel, Genesis Shepherd

Cauldron of Souls

Clock of Omens

Atog

How it works

1. Activate Cauldron of Souls by tapping it, giving two nontoken artifact creatures persist until end of turn.
2. Activate Clock of Omens by tapping the nontoken artifact creatures, untapping Cauldron of Souls.
3. Activate Atog by sacrificing one of the nontoken artifact creatures that doesn't have a -1/-1 counter on it.
4. When the creature dies, its persist ability and Szarel triggers.
5. Resolve the persist trigger, returning the creature from your graveyard to the battlefield.
6. Resolve the Szarel trigger, putting a number of +1/+1 counters on the other artifact creature.
7. Resolve the Atog ability.
8. Repeat from step 3 once, instead sacrificing the creature who had counters placed on it in step 6.
9. Repeat from step 1.

This brilliant loop turns the graveyard into an engine of endless growth by combining recursive artifact sacrifice with a clever stat-buffing payoff. You set the stage using Cauldron of Souls to grant persist to your artifact creatures, which then feed Atog's appetite while simultaneously paying the tapping cost for Clock of Omens to keep the Cauldron active. As these creatures die and return, Szarel, Genesis Shepherd triggers off each sacrifice to pump your creatures with massive +1/+1 counters—which conveniently counteract the -1/-1 counters from persist, allowing the cycle to repeat indefinitely.