Combat Celebrant + Displacer Kitten + Spellbinder + Concordant Crossroads

Combat Celebrant

Displacer Kitten

Spellbinder

Concordant Crossroads

How it works

1. Declare Combat Celebrant and the creature with Spellbinder attached as attackers, choosing to exert Combat Celebrant as it attacks.
2. Combat Celebrant triggers, causing you to untap all other creatures you control and to get an additional combat phase after this one.
3. Deal combat damage using the creature that has Spellbinder attached.
4. Spellbinder triggers, causing you to copy a card exiled with it, and cast the copy without paying its mana cost.
5. Displacer Kitten triggers, blinking Combat Celebrant.
6. Resolve the spell cast in step 4.
7. Repeat each combat phase.

This cunning loop turns a single extra combat step into an endless sequence of assaults, powered by Combat Celebrant and its ability to grant additional combat phases when exerted. To break the restriction of exerting only once, Displacer Kitten steps in as the engine: every time you cast a noncreature spell, it blinks the Celebrant, resetting its state so it can be repeatedly exerted upon each new attack. The missing link is Spellbinder, which is equipped to an attacker and triggers upon dealing combat damage to cast an imprinted instant without paying its mana cost—which conveniently serves as the noncreature spell needed to trigger the Kitten. Meanwhile, Concordant Crossroads ensures your freshly blinked Combat Celebrant can attack immediately in every subsequent combat phase without waiting for summoning sickness.