Artifact, 3 (3) As long as Trinisphere is untapped, each spell that would cost less than three mana to cast costs three mana to cast. (Additional mana in the cost may be paid with any color of mana or colorless mana. For example, a spell that would cost {1}{B} to cast costs {2}{B} to cast instead.)1
Illus. Tim Hildebrandt
12/1/2004: Trinisphere's ability affects the total cost of the spell. It is applied *after* any other cost increasers or cost reducers are applied: First apply any cost increases. Next apply any cost reducers. Finally look at the amount of mana you have to pay. If it's less than three mana, you'll pay three mana.
12/1/2004: Even with a cost reducer in play, spells can't cost less than three mana to play.
12/1/2004: If a spell costs at least three mana due to additional costs, such as kicker costs, that's fine.
12/1/2004: You still need to pay any additional nonmana costs the spell has, such as sacrificing a creature or discarding cards.
12/1/2004: Playing a creature with morph face down already costs three mana, even though the converted mana cost of the face-down spell is zero, so Trinisphere normally doesn't modify the total cost of a face-down creature spell. However, if Dream Chisel is reducing that cost while Trinisphere is in play, you'll still have to pay three mana for the spell.
Darksteel
(Rare)