The light dragon was revived by Azroth using the Temporary Resurrection skill.
Normally, the revival effect of this skill lasts for twenty-four hours, but revival time is greatly reduced if the revived person uses too much of their power.
The light dragon was a mid-level Rank Six Core Evolver, and because it used too much of its power, it was about to disappear after fending off the attack of the magic cannons and attack formations.
Azroth had instructed the light dragon to provoke the Demon Empire in the name of the Dragon Islands. So when the light dragon felt it would soon disappear, it didn't hesitate and decided to self-destruct to cause as much damage as possible.
Because it was about to disappear, the energy released upon its self-destruction was actually much lower than that of a Rank Six Core Evolver's self-destruction.