Mastery of Ice and Fire

(Player's Guide to Eberron, page 126, DnD 3.5)

[General]

You have learned to calculate the precise locations of Fernia and Risia at any given time, and to use that knowledge to enhance cold and fire spells that you cast.

Prerequisite

Enlarge Spell, Knowledge (the planes) 2 ranks, Spellcraft 4 ranks

Benefit

You can spontaneously apply the effect of the Enlarge Spell metamagic feat to any spell you cast that has the cold descriptor or the fire descriptor. Doing this has no effect on the spell's level or casting time.