How to kill Kosis ?

How to kill Kosis ? Other mini boss with baily, is ok to dodging his attacks, but Kosis i think it's bad design example.
How much defences and mitigations i need to be enable to kill him and evoid his teleport=oneshoot mechaniks ?

Allso, how can i evoid stun from mobs ? with out taken Unwavering Stance and Kaoms Boots ?
thnx for ansver.

I did a simulacrum deathless yesterday (which was a surprise for me). Mobility is definitely a necessity, but so is high damage to reduce the window you're exposed (aka fighting).

I did it on my champion cycloner. Can't really give your reliable numbers since one with nothing doesn't work in pob (and manually calculating might miss some factors) but my average tooltip dps shows as a little over 200k with over 7 attacks per second.

I'm pretty sure the tooltip doesn't factor things like impale, but suffice it to say ever since legion I've had to focus on skills I know how to scale up well.