Isochron Scepter + Narset's Reversal + Hidden Strings + Chromatic Orrery

Isochron Scepter

Narset's Reversal

Hidden Strings

Chromatic Orrery

How it works

1. Activate Chromatic Orrery's first ability by tapping it, adding 5.
2. Cast HIdden Strings by paying 2, targeting any two applicable targets.
3. Activate Isochron Scepter by paying 2 and tapping it, casting a copy of Narset's Reversal without paying its mana cost.
4. Resolve Narset's Reversal, returning Hidden Strings to your hand and creating a copy of it, targeting Isochron Scepter and Chromatic Orrery.
5. Resolve the copy of Hidden Strings, untapping Isochron Scepter and Chromatic Orrery.
6. Repeat.
7. Once you have infinite mana, you may use Chromatic Orrery's second ability if you control a colored permanent and/or untap any other permanent(s) you control.

This ingenious loop transforms Chromatic Orrery from a simple mana rock into a powerhouse by taking full advantage of how spells interact on the stack. With Chromatic Orrery providing the necessary colorless energy and letting you spend your mana as any color, you cast Hidden Strings to begin the chain. Isochron Scepter holds the key by repeatedly casting Narset's Reversal for a mere two mana, bouncing your original Hidden Strings right back to your hand while copying it to untap both the Scepter and the Orrery. By looping this sequence indefinitely, you generate infinite mana and storm count, allowing you to cycle through your entire deck using Chromatic Orrery's card-drawing activation.