Infinite card drawInfinite colored manaInfinite colorless manaInfinite draw triggersInfinitely large creature until end of turnInfinite untap of creatures you control
How it works
Activate Chromatic Orrery's first ability by tapping it, adding 5.
Activate Karn by paying 1, causing Chromatic Orrery to become an artifact creature until end of turn.
Activate Umbral Mantle's equip ability by paying 0, attaching it to Chromatic Orrery.
Activate Chromatic Orrery by paying 3 and untapping it, giving it +2/+2 until end of turn.
Activate Chromatic Orrery's first ability by tapping it, adding 5.
Repeat from step 4.
Once you have infinite mana, you may instead use Chromatic Orrery's second ability if you control a colored permanent.