Flame Walk

By means of this spell the caster is able to empower himself or herself, or another creature of man-size and comparable mass, to withstand non-magical fires up to temperatures of 2,000° F. 

It also confers a +2 bonus to saving throws against magical fires. 

For every level of experience above the minimum required to create the dweomer (5th), the caster can affect an additional man-sized creature. This growing power enables multiple individuals, or one or more of greater than man-size and mass, to be affected by the flame walk spell. For instance, an 11th-level caster could empower both himself or herself and a steed such as a horse to move in molten lava. (Consider a horse to be equivalent to 6 humans for purposes of this spell; conversely, halfling-sized creatures count as 1 human apiece, and pixie-sized creatures are considered equivalent to ¼ human each.) 

The material components of the spell are at least 500 gp of powdered ruby and the cleric's holy/unholy symbol.