Boonweaver Giant + Unhallowed Pact + Yahenni, Undying Partisan

Boonweaver Giant

Unhallowed Pact

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Boonweaver Giant
2. When Boonweaver Giant dies, Unhallowed Pact triggers, returning Boonweaver Giant from your graveyard to the battlefield
3. When Boonweaver Giant enters, it triggers, returning Unhallowed Pact from your graveyard to the battlefield attached to Boonweaver Giant.
4. Resolve the Yahenni ability from step 1.
5. Repeat.

This elegant loop creates an endless cycle of sacrifice and rebirth by letting Boonweaver Giant and Unhallowed Pact constantly resurrect each other. When you sacrifice the Giant to Yahenni, Undying Partisan's activation, Unhallowed Pact triggers from the graveyard to bring the Giant right back, which in turn triggers the Giant's ability to fetch the Unhallowed Pact back to itself. Because Yahenni's sacrifice ability requires no mana, you can repeat this process endlessly to flood the battlefield with infinite enters-the-battlefield triggers, leaves-the-battlefield triggers, and creature deaths while growing Yahenni into an infinitely massive threat.