Whirlwind Attack
Does anyone notice that this ability does not have consistent damage? I did ~39k dmg on Subject Alpha once.
It is a cumulative attack like Hundred Blades. The more you hit the higher the number shown. If you are crippled/chilled you will move a lot less while using whirlwind and as such hit whatever you are standing on a lot more.
Sounds to me like he crippled you while you were on top of him then used whirlwind.