Agni, Spirit of Fire

Bestow 2{r} (If you cast this card for its bestow cost, it's an Aura spell with enchant land. It becomes a creature again if it's not attached to a land.)
Enchant Mountain
As long as Agni, Spirit of Fire is enchanted onto a target Mountain land card you control, you may pay {0} rather than pay the mana cost for
red mana cost spells.