Combat Arts/Heat Dash
There are five Heat Dash Combat Arts available to Spheromancers: two first-level, two second-level, and one third-level art.
Ashen Mine

Place a mine that explodes when enemies are nearby.
Ashen Mine is a heat-elemental, level one Dash-type Combat Art. It costs 1 CP to activate and 1 SP to use.
When using it, Lea dashes a distance of 1.5 normal dashes, leaving behind a mine. The mine arms after 1 second, ready to explode when your enemies come near. If none do after 5 seconds, the mine explodes on its own. The explosion hits once damaging and knocking back enemies.
Surprisingly, Ashen Mine does not inflict Burn, but its explosion radius is quite wide. This art is best used to damage or shake off pursuing enemies, so that several of them are standing on top of it when the mine arms. Otherwise, it doesn't last long enough or deal enough damage to lay extensive minefields.
Apollo uses this combat art during his second and third duels against Lea.
Crimson Strike

Performs a fierce whirl attack, engulfing your enemies in flames.
Crimson Strike is a heat-elemental, level one Dash-type Combat Art. It costs 1 CP to activate and 1 SP to use.
Upon using Crimson Strike, Lea dashes the same distance as Azure Strike, spinning rapidly surrounded by whirls of flame, damaging and knocking back all enemies she passes through. Inflicts Burn.
The same uses for Azure Strike apply to Crimson Strike. More than that, the two are almost identical, save for Crimson Strike's fieriness and slightly wider width.
Pentafists can also use this combat art, as shown by Emilie.
Mine Valley

Dash and place multiple mines which can seek enemies when not touched.
Mine Valley is a heat-elemental, level two Dash-type Combat Art. It costs 2 CP to activate and 3 SP to use.
When using this art, Lea dashes a distance of approximately 3 normal dashes, leaving behind 3 mines similar to Ashen Mine along her path. All these mines home in on and explode against the first enemy any of them encounter.
Because of its longer dash distance and proximity radius, Mine Valley is far more reliable against pursuers than Ashen Mine. Curiously, if you use Mine Valley multiple times to lay several mines, all of them converge on the triggering enemy, and continue if you keep laying more mines. None of Ashen Mine's mines participate.
Crimson Stream

Surround yourself with fire and dash a long way, leaving hot damaging magma on the ground. Causes Burn.
Crimson Stream is a heat-elemental, level two Dash-type Combat Art. It costs 2 CP to activate and 3 SP to use.
Upon using Crimson Stream, Lea dashes a distance of approximately 5 normal dashes, leaving a trail of churning flames in her wake for 5 seconds. Inflicts Burn.
An upgrade of Crimson Strike in many respects, much like Azure Surge is to Azure Strike. The trail of fire is effective against many enemies at once, making this art best for dashing through large groups to Burn all of them. Subsequent use extinguishes the previous trail of fire.
Scarlet Rain

Mark enemies by dashing through them which will be bombarded by a blazing meteor shower.
Scarlet Rain is a heat-elemental, level three Dash-type Combat Art. It costs 3 CP to activate and 6 SP to use.
When using this art, Lea dashes a distance of approximately 5 normal dashes, surrounded by bright whirls of flame. Lea pauses briefly, then can act on her own. If she struck any enemies, they are marked with revolving targeting diamonds and a series of around 13 fiery meteors bombard the marked targets. Inflicts Burn.
Since each meteor explosion damages everything around it, Scarlet Rain is most effective against tightly clustered enemies in confined spaces. This is one of few ways to deal damage from above, bypassing the protection of some enemies such as the iron mask of Bovines.