Tidespout Tyrant + Mana Vault

Tidespout Tyrant

Mana Vault

How it works

1. Cast Mana Vault by paying its mana cost.
2. Tidespout Tyrant triggers, returning a nontoken permanent that can be cast using CC from the battlefield to your hand.
3. Activate Mana Vault by tapping it, adding CCC
4. Cast the nontoken permanent returned in step 2 by paying its mana cost.
5. Tidespout Tyrant triggers, returning Mana Vault from the battlefield to your hand.
6. Repeat.