Exploit making Caustic Spatter deliver attacks damage in a range of 300 000 to 800 000 nature dmg

A rogue from Tichondrius server litteraly oneshotted several time my ilvl479 demon hunter in orgrimmar. Each time the attacks are in a range between 300 000 and 800 000 dmg and it is coming from Caustic Spatter hit. I got screenshot of the combat log. Probly an exploit.