Text (SC+errata): 2/2. ; Creature spells you cast with converted mana cost 6 or more cost {2} less to cast. [Oracle 2009/07/08]
Two of these can be applied to a single spell with converted mana cost of 6 or more. This effect, like others that modify costs, does not alter the mana cost of the spell. So even after the cost to be paid is reduced by {2}, the converted mana cost is still greater than 6 because it is unaltered. [D'Angelo 2006/09/30]