Thermal Transfer

Use transmutation magic to sap an area of heat only to pour that heat out on another area on the following turn.

On initial cast, you create the Ice Sphere. The heat from the area effected by the Ice Sphere is stored in the diamond used to cast this spell. On your following turn you must use an action to transfer the heat to the ruby and cast the Fire Sphere or the stored heat explodes from the Diamond in your hand and you and any creature in range are effected by the Fire Sphere as normal and the spell ends.

Ice Sphere: Every creature within a 10 foot radius sphere centered on any point within range that you can see must make a CON Saving throw or take 4d6 Cold damage or half as much on a successful save. The entire area of the sphere and any nonmagical objects that are not being worn or carried are encased in a layer of ice causing the area to become difficult terrain until the end of your next turn. All nonmagical, liquid within the sphere is instantly frozen solid but will immediately begin to melt at a natural rate. Any nonmagical flames within the sphere are doused. If the Ice Sphere is cast on lava, the lava is instantly cooled enough to touch without harm and the Fire Sphere is enhanced.

Fire Sphere: All creatures within a 10 foot radius sphere centered on any point within range that you can see must make a Dex saving throw or take Fire damage equal to the cold damage dealt by the Ice Sphere or half as much on a successful save. Any creatures that fail their save and any nonmagical, flammable objects that are not being worn or carried are ignited with nonmagical flames and take 2d6 Fire damage at the start of every turn until they or an allied creature use an action to put them out. This damage is rolled separately from the initial damage. Nonmagical, flammable objects burn until they are put out or destroyed. (If the Ice Sphere was cast on lava, add an additional 3d6 to the initial damage of the sphere and increase it's radius by 5 feet.)

This spell's damage may not be transmuted to another damage type by any means.

 The gems used in casting this spell must be nonmagical but may be set in any nonmagical non flammable object such as a staff, shield, piece of armor Etc...

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the initial damage increases by 1d6 for each slot level above 4th and the Fire damage from the ignition effect increases by 1d6 per turn

When cast at 6th level or higher, a creature that fails a saving throw against the Cold damage sphere has its movement reduced to 0 until they use an action to free themselves from the ice.