Sinking Feeling + Hex Parasite + Kelpie Guide + Chromatic Orrery

Sinking Feeling

Hex Parasite

Kelpie Guide

Chromatic Orrery

How it works

1. Activate Chromatic Orrery's first ability by tapping it, adding 5.
2. Activate Kelpie Guide's first ability by tapping it, untapping Chromatic Orrery.
3. Activate Kelpie Guide by paying 1 and putting a -1/-1 counter on it, untapping it.
4. Activate Hex Parasite by paying 2, removing the -1/-1 counter from Kelpie Guide and giving Hex Parasite +1/+0 until end of turn.
5. Repeat.
6. Once you have infinite mana, you may instead use Chromatic Orrery's first ability to draw infinite cards.

This loop relies on transforming Sinking Feeling's activation cost into a net-positive mana exchange, brilliantly enabled by Chromatic Orrery letting you spend your colorless mana as any color to pay for Hex Parasite's hybrid life-or-mana cost. While Sinking Feeling locks down the enchanted creature and Kelpie Guide provides the tapping mechanism to untap your mana source, it is Hex Parasite that cleans up the lingering -1/-1 counters to keep the creature alive and the engine running. Once you have this perpetual motion machine of untaps and mana generation established, you can use Chromatic Orrery to draw your entire deck and claim victory.