Orvar, the All-Form + Throne of Eldraine + Clockspinning + Mirror Box

Orvar, the All-Form

Throne of Eldraine

Clockspinning

Mirror Box

How it works

1. If able, activate Throne of Eldraine's first ability by tapping it, adding that can only be spent to cast blue monocolored spells.
2. Cast Clockspinning with buyback by paying 3, targeting Throne of Eldraine.
3. Orvar's first ability triggers, creating a copy of Throne of Eldraine. Choose "Blue" as its color as it enters the battlefield.
4. Resolve Clockspinning, returning it to your hand.
5. Repeat.