Eternal Taskmaster + Coretapper + Magistrate's Scepter

Eternal Taskmaster

Coretapper

Magistrate's Scepter

How it works

1. Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter.
2. Activate Coretapper's second ability by sacrificing it, putting two charge counters on Magistrate's Scepter.
3. Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, taking an extra turn after this one.
4. Declare Eternal Taskmaster as an attacker.
5. Eternal Taskmaster triggers, causing you to pay 2 to return Coretapper from your graveyard to your hand.
6. In your postcombat main phase, cast Coretapper by paying 2.
7. Repeat each turn.