Primalcrux

• WWizards of the Coast2008-08-01
  Official Ruling
  This will count the number of symbols in its mana cost while it's on the battlefield. The ability functions while it's in other zones, but since it isn't a permanent while in those zones it won't count itself.
• WWizards of the Coast2008-08-01
  Official Ruling
  Chroma abilities check only mana costs, which are found in a card's upper right corner. They don't count mana symbols that appear in a card's text box.
• WWizards of the Coast2008-08-01
  Official Ruling
  Chroma abilities count hybrid mana symbols of the appropriate color. For example, a card with mana cost has two red mana symbols in its mana cost.

Rulings via Scryfall