Heart of Fire

You feel a sudden flame burning within you.   This spell converts part of your body into elemental fire, which speeds your step and toughens your flesh. You gain a +10-foot enhancement bonus to your land speed and resistance to fire 20.   Furthermore, while this spell is active, you can activate a fire shield effect (as the spell; fire-based protection only) on yourself as a swift action. This benefit lasts for 1 round per level, at the end of which time the spell's entire effect ends.   If heart of fire is active on you at the same time as heart of air, heart of earth, or heart of water, you gain light fortification. If all four of these spells are active on you at the same time, you become immune to extra damage from critical hits and sneak attacks.
 

You suffuse your body with elemental fire, igniting a flame within your veins. For the duration, your land speed increases by 10 feet, and you gain resistance to fire damage.   As a bonus action, you can activate the effects of the Fire Shield (warm shield only) spell on yourself for 1 Minute, after which time this spell ends.   If you are affected by both this spell and either Heart of Air, Heart of Earth, or Heart of Water, critical hits scored against you become normal hits instead.   At Higher Levels. When you cast this spell using a higher level spell slot, increase your land speed by 5 feet for each slot level above its base level.