Chromatic Orrery + Umbral Mantle + The Blackstaff of Waterdeep

Chromatic Orrery

Umbral Mantle

The Blackstaff of Waterdeep

How it works

1. Activate Chromatic Orrery's first ability by tapping it, adding 5.
2. Activate The Blackstaff of Waterdeep by paying 2 and tapping it, causing Chromatic Orrery to become an artifact creature.
3. Activate Umbral Mantle's equip ability by paying 0, attaching it to Chromatic Orrery.
4. Activate Chromatic Orrery by paying 3 and untapping it, giving it +2/+2 until end of turn.
5. Activate Chromatic Orrery's first ability by tapping it, adding 5.
6. Repeat from step 4.
7. Once you have infinite mana, you may instead use Chromatic Orrery's second ability.

This loop turns a simple mana rock into a self-sustaining engine by transforming it into an active creature. Once Chromatic Orrery is animated into a 4/4 artifact creature by The Blackstaff of Waterdeep, it becomes a legal target for Umbral Mantle's free equip ability. Tapping the Orrery for its five-mana production provides more than enough fuel to activate the Mantle's untap ability, leaving you with a net profit of mana and a progressively larger creature. Thanks to Chromatic Orrery's passive ability letting you spend your mana as any color, you can easily cycle this loop into infinite colored mana, an infinitely large creature, and eventually draw your entire deck.