Havi, the All-Father + Gerrard, Weatherlight Hero + Grimgrin, Corpse-Born

Havi, the All-Father

Gerrard, Weatherlight Hero

Grimgrin, Corpse-Born

How it works

1. Activate Grimgrin by sacrificing Gerrard.
2. When Gerrard dies, it and Havi trigger.
3. Resolve the Havi trigger, returning up to one legendary creature card with mana value 3 or less from your graveyard to the battlefield.
4. Holding priority, activate Grimgrin by sacrificing Havi.
5. When Havi dies, it triggers, returning Gerrard from your graveyard to the battlefield.
6. Resolve the Gerrard trigger from step 2, failing to exile it as it is no longer in your graveyard and returning Havi from your graveyard to the battlefield.
7. Resolve the Grimgrin abilities from step 1 and 4.
8. Repeat.