Temple of chaos Chimeral inscribed ultimatum

Can't complete 3rd challange where i need to collect the things, The mobs keep spawning, i have to go up the elevators. and mobs follow ( teleport ) and just insta kills me. is this by design or is it meant to be this way

Your post is pretty hard to follow. Collect the things?

If you're talking about the challenge where you need to collect the soul cores and place them in pedestals, then you need to do that.

The elevators you're meant to ascend glow bright orange and have a switch next to them.

Mobs spawn down other elevators, but if they aren't glowing you can't ride them.

It's meant to be a challenge to unlock further ascendancy levels. Mobs insta killing you sounds like an issue with your items or build, or the ultimatum challenges you've selected. Is there something specific you're trying to request here? If not, then the usual solution is "upgrade items, level up, play the rest of the game for a bit, and come back when the challenge is easier". Enemies are levelled based on the token you insert at the start of the temple, so if you outlevel them by a bit then the challenge will be respecively easier.