How can you create a combo with Biomancer's Familiar, Umbral Mantle, Arixmethes, Slumbering Isle?
user
[START OF COMBO]This combo can be formed with Biomancer's Familiar, Umbral Mantle, Arixmethes, Slumbering Isle

Color identity: GU
Mana cost: 
Steps:
  1. Activate Arixmethes by tapping it, adding {U}{G}.
  2. Activate Arixmethes by paying {1} and untapping it, giving it +2/+2 until end of turn.
  3. Repeat.[END OF COMBO STEPS]

Result:
  - Infinite colored mana
  - Infinitely large Arixmethes until end of turn[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
  - Arixmethes is a creaure and does not have summoning sickness.
  - Umbral Mantle attached to Arixmethes.
[END OF COMBO PREREQUISITES]
assistant