Works on all spells with the type Creature, even if the spell has another type like Artifact or Enchantment.

Multiple Gates are cumulative. Two will reduce the cost by up to {4}, and so on.

Only works for its controller, not all players.

Only reduces the generic mana portion of a spell's cost. If the cost does not include generic mana or includes less than {2}, you get a reduced or null effect from this card.