We have been doing ptr last night and Thadius seems to be tuned for 40 man grp, like in classic.
In 20 players group on normal, we had only 90% dmg increase (from 9 other players with the same polarity). We tried him 2 times and with all players alive till berserk we were not able to push him under 40%.
I have talked with other ptr groups and best try that I am aware of was around 30%.
So, Thadius is overtuned big time right now.
Either cut hp in half or provide more than 10% per person, otherwise he is impossible to kill with 20 players.
10% per player was fine in classic, when we had 20 players per side. In sod, it is rare to have 40 players in raid.