He is gloomy and reticent, and symbolized by illusion, fear, and the Spiritmaster class. Thinking of lives very lightly, he enjoys killing and revels in war. Kaisinel is such a horrifying being that even other Empyrean Lords prefer not to interact with him.
Ariel, while asking her unnamed subordinate how is the fight is going in Tiamaranta, he reveals that Kaisinel is the commander of the Sanctum Expeditionary Force and that his task is to destroy Tiamat. However, according to Vaizel's reports, he is having a difficult time not just because of the Balaur, but because of the Asmodians and Marchutan.
The Reian-Elyos-Asmodian united front drives Tiamat into a corner. When the Reian Sorcerers find a way into her hideout, the dragon's fate is settled. In the final battle she is killed by the player who seals the Siel's Relics and gets help from Kaisinel. Without the relics Tiamat is weakened and becomes no match for Kaisinel.