Ascendant Riftwalker abilities?

[Miothan]

Cans someone explain to me what the Ascendant Rifltwalker actually does and how to avoid it?

I know he:

Goes Immune and casts something which i can avoid by standing next to him
Summons a Shambler, and spawns a blue ring
Casts a lot of Rift Storms
Casts swirling Lightning torrent
Gets a fire symbol above hes head (no idea what that does)

I have tried to kill him quite a lot of times now and i just don't know if i should stand inside the blue circle when a shambler spawns or avoid it, should i damage Riftwalker when he gets the fire symbol above hes head or not? what does it even do? so many questions but no actual information on what he does anywhere that i can find, which is quite frustrating.

[Lynderika]

There's a few guides around, but you mostly got it right. He has 4 attacks :

1) Retaliate, there's a cold animation above him and as you said he get immortal shortly before, avoided by staying close
2) Fire aura, there's a fire animation above him and a cold circle and a shambler appear at the same time somewhere around, shortly after the animation change and most of the arena get hit by big fire damage / sec, unless you stay inside the cold circle. There's a few places on the edge of the maps that work as well but they're very small and unreliable.
He can spam them so stay alert
3) Lightning swirl : See which direction he's facing to know where he'll throw it
4) Rift storm : some happens randomly without him doing anything, and I think it depend on your position a little bit, but he can cast lots of them in one go.

The common strategy is max lightning resist to not care about the swirl, and stay close most of the time, only moving to get in the cold circle. You can attack him anytime

[ziigii]

I would always stand in the ring as I would die to cold dmg otherwise. ( Not 100% sure this is the best way of doing things)
And use teleport to move around as much as possible to reduce desync.

[Miothan]

There's a few guides around, but you mostly got it right. He has 4 attacks :

1) Retaliate, there's a cold animation above him and as you said he get immortal shortly before, avoided by staying close
2) Fire aura, there's a fire animation above him and a cold circle and a shambler appear at the same time somewhere around, shortly after the animation change and most of the arena get hit by big fire damage / sec, unless you stay inside the cold circle. There's a few places on the edge of the maps that work as well but they're very small and unreliable.
He can spam them so stay alert
3) Lightning swirl : See which direction he's facing to know where he'll throw it
4) Rift storm : some happens randomly without him doing anything, and I think it depend on your position a little bit, but he can cast lots of them in one go.

The common strategy is max lightning resist to not care about the swirl, and stay close most of the time, only moving to get in the cold circle. You can attack him anytime

Thanks for that info, took a break while i was hoping for some info, and this is just what i needed im sure ill be able to get him now that i know what to do.

EDIT: After a few more tries i managed to get him down with the bonus quest done a major problem i had was not understanding that i had to stay in the blue ring until the fire thingy was done, i thought i could walk out of it as soon as i killed the shambler