How can you create a combo with Mystic Decree, Stormtide Leviathan?
user
[START OF COMBO]This combo can be formed with Mystic Decree, Stormtide Leviathan

Color identity: U
Mana cost: 
Steps:
  1. Mystic Decree causes all creatures to lose flying and islandwalk.
  2. Because Stormtide Leviathan prohibits creatures without flying or islandwalk from attacking, no creatures can attack.[END OF COMBO STEPS]

Result:
  - Creatures cannot attack[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
[END OF COMBO PREREQUISITES]
assistant