I am extremely hesitant as to whether or not I should put this ability in my set. One version of this ability restricts the player in terms of what kind of spells can be cast with the mana. Alternatively, I could make it so that the ability only gives one more mana than it costs to activate. Anyway, let me know what you think. I don't want to create an ability that, realistically, would only become degenerate combo fuel.

­Pyretic Ritual is basically not much use except as combo fuel.

Did you see the Manacycling we put in the Community Set? That version has creatures cast Manamorphose rather than Pyretic Ritual: it just filters mana colours, but it cantrips as well. Frenzied Yeti is our equivalent to this card, and Loretower Warden is an example two-colour card.