Klarrgas appears in every 8th Corridor stage. Rarely drops a Tendai Uyaku. After defeating it, there is a chance to obtain its skin which can be used when merging minions. This minion's skin has the skinventory-ID 7.
All bosses in the Eternal Corridor use infinite Mana, which allows them to use their attacks as often as they wish. Uses its Horn - Flesh-To-Stone + Accuracy, Fang - Sleep + Accuracy and Claw - Poison + Accuracy attacks in order to cause several negative status to unaware players.
Hints on defeating this boss
As it is completely imuune to elemental sources and standard attacks, it takes only 1 damage from these attacks. A merged minion resistant against the three possible status can disrupt Klarrgas' strategy, nullifying possible problems. Sel Selahm can temporarily cause the same effect. Use negative status attacks or absorb its HP to defeat it, or score a Critical and finish it off.
It is the only minion completely resistant to elements and standard attacks, making it a feared enemy.