Try it with Viper Bite, godly stuff man...:

DRG uses Double Thrust!
Beetle takes 178 dmg
THF uses Sneak Attack!
THF uses Trick Attack!
THF uses Viper Bite!
Beetle takes 498 dmg
Skillchain: Distortion!
250 damage from Skilchain!
BLM readies BlizzardII
RDM readies WaterII
WHM readies Blizzard(yes i burst too if i have mp and if things are going well and the renkei is strong vs the mob)
WHM MB 107 dmg!
BLM MB 290 dmg!
RDM MB 178 dmg!
Beetle Falls(from full life)