Muldrotha, the Gravetide + Coretapper + Magistrate's Scepter

Muldrotha, the Gravetide

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, causing you to take an extra turn after this one.
4. Cast Coretapper from your graveyard by paying 2.
5. Repeat each turn.