Pure flame filled me, the joyous heat of full summer, and I exalted in the sudden, overflowing life of it. It met the tiny spark of hope still glowing within me and the two multiplied.— Harry DresdenWhen in use, Summer fire provides Harry Dresden raw power to draw upon, fueling his spells, his weakened body, and for a time keeping the cold of Winter at bay. The use of Summer fire by a magic wielder allows agents of Summer to locate the wielder whenever they use that type of magic again. After Dresden used Summer fire to fuel his fire spells in Arctis Tor, Eldest Gruff was able to use Summer fire to zero in on Dresden's location the moment he used fire magic on Demonreach island.
In the seriesEdit
In Proven Guilty, Lily, the Summer Lady, gives Harry Dresden Summer fire to use in the form of a glowing butterfly. He draws upon it when he completely runs out of energy as he battled the Scarecrow.
In Small Favor the Summer fire within Fix, the Summer Knight, prevents snowflakes from falling on him. Each snowflake seems to find a way around him on its way to the ground, and although he only wears jeans and a green silk t-shirt, he is totally unaffected by the cold.
Summer fire is also used by the agents of Summer, namely Eldest Gruff, to lock onto Harry Dresden's location whenever he uses fire magic, which was possible because Dresden's fire magic became keyed to Summer when he used Summer fire to fuel said magic at Arctis Tor. Knowing this, Mab takes away Dresden's blasting rod, along with all of his memories of fire magic, in an attempt to prevent him from using it and revealing his position to Summer.
In Cold Days, Lily, distracted by Maeve's lies, hurls a huge wall of Summer fire at Harry Dresden. He managed to protect himself and Fix from the flames with Winter ice. Lily, seeing that he survives, becames enraged, with Summer fire replacing her eyes. After talking with Dresden, she then launches a miniature star of Summer fire directly at his head, too concentrated for him to block, only for Fix to stand up and deflect the bolt with his Faerie Sword, which is partially melted in the process.