Thassa's Rebuff

• WWizards of the Coast2013-09-15
  Official Ruling
  Hybrid mana symbols, monocolored hybrid mana symbols, and Phyrexian mana symbols do count toward your devotion to their color(s).
• WWizards of the Coast2013-09-15
  Official Ruling
  Numeric mana symbols (, , and so on) in mana costs of permanents you control don't count toward your devotion to any color.
• WWizards of the Coast2013-09-15
  Official Ruling
  Mana symbols in the text boxes of permanents you control don't count toward your devotion to any color.
• WWizards of the Coast2013-09-15
  Official Ruling
  If an activated ability or triggered ability has an effect that depends on your devotion to a color, you count the number of mana symbols of that color among the mana costs of permanents you control as the ability resolves. The permanent with that ability will be counted if it's still on the battlefield at that time.

Rulings via Scryfall