Doom's Time Platform + Clockspinning + Time Walk

Doom's Time Platform

Clockspinning

Time Walk

How it works

1. Cast Time Walk by paying its mana cost, causing you to take an extra turn after this one.
2. Declare any creature as an attacker. When you do, Doom's Time Platform triggers, exiling Time Walk from your graveyard with two time counters on it.
3. Move to your next turn. At the beginning of your upkeep, Time Walk's suspend ability triggers, removing a time counter from it.
4. Cast Clockspinning with buyback by paying 3, removing a time counter from Time Walk and returning Clockspinning to your hand.
5. Time Walk's suspend ability triggers, causing you to cast it without paying its mana cost.
6. Resolve Time Walk, causing you to take an extra turn after this one.
7. Repeat from step 2 each turn.