Don’t understand

[viscid cloak]

Can someone explain to my why his mortal strike did so much more damage than mine with only 3 more casts???

Trying to figure out it why he did 300k more than I did.

I am Paaxx btw

https://www.warcraftlogs.com/reports/compare/dB1arpXTzkNFbVLj/D2JZdVhM93nLtBxm?fight=11%2C53&type=summary&source=35%2CWooflkinz