Full: Pyroclastic fragments spew forth, dealing 80 damage to target foe and all adjacent foes. Affected foes are Crippled and begin Burning for 7 seconds. This skill causes any powder keg in target's hands to explode.
Concise: Projectile: deals 80 damage and inflicts Burning and Crippled conditions (7 seconds) on target and adjacent foes. Causes any powder keg in target's hands to explode.
The skill description states the effect for a level 20 caster using the skill on an AR 60 target. As usual, character level differences in damage calculation come into effect. As Cyndr is level 29, he has an extra damage multiplier of 227/40 which raises the stated 80 figure to about 127. Being a level boss, his damage is further doubled to 254.