What if I told you, you can stop it? Btw it's during his cooldowns, with dark soul etc. You dont stay in front of a frost mage standing still while he spams fb with iceform, into Glacial. (That can hit 1mill+ too)
Are you like completely clueless? Soul harvest is a 20% dmg increase, nowhere near what "dark soul" was in the past. With 0 cd's up chaos bolts will be turret spammed for 700k +/- 150k (ish) depending on mastery rng with 1.5 sec cast time.
Or if you know someone is gonna line you till the end of days, just go cremation shadowburn and spam instants for 200k dps with no pause.