On her attacks, Mokou takes damage as well.
Example 1: Mokou uses her Multiattack, attacking with Firebolt four times. On her first Firebolt, she scores a hit. She rolls 4d6, scoring a 15. The target takes 15 fire damage, and Mokou takes 7 fire damage.
Her second attack misses. She rolls 4d6, scoring an 11. The attack missed, so the target takes no damage, but Mokou still takes 5 fire damage.
Mokou can use Spontaneous Combustion to escape dangerous situations. For instance, if Mokou becomes restrained, she can use it to kill herself and revive with Phoenix to escape.
Note that Mokou's healing from Immortal is meant to occur before damage taken from Ignition.