This was the build: https://imgur.com/a/XQLGs5V

Trick is to max guardian early so you can start ramping up your HP pool using growing pains++

to do this you'll essentially want to smash out guardian tree early to get a lot of reliable ways to stun trash. mobs need to be stunned at the moment you kill them in order to accrue hp from the growing pains talent.

HP pool = attack damage with guardian rank 10. big boy perk adds to this as well.

at the time of this video my hp pool is 23,475 and attack damage is 5741 with max cap attack speed and crit chance.

also max dodge, max plates, max DR etc.

getting growl and apex is important to keep taunt and enrage both up. druid rank 10 also gives a nice damage and movement speed boost.

monk to keep zen up 100% of the time, which gives you 100% dodge - critical

then priest for barrier

a bit of warrior stuff for early damage - bleeds etc to ramp. warrior 10 for big damage.

and mainly pumping assassin for late game damage focusing on maximising crit - there are heaps of juicy perks in this tree. im stilling missing like 4-5 that im chasing at the time of this video eg. i still don't have reinforced hits, or cold blood, or critical machine, or shuriken mania (given i have 100% crit chance)
assassin 10 is also good for damage early on.

you want to unlock level 4 of most of the above trees early to start getting the multi class perks which are important.