Trialmaster working as intended?

There is a new mechanic not covered in any guides I've found which completely wiped me and a friend. We thought it was an isolated incident, but lo and behold: https://www.reddit.com/r/PathOfExile2/comments/1k1s0d2/omae_wa_trialmaster_2025/

How in the world are we supposed to overcome that?! Is this a DPS failsafe that causes instant defeat? (e.g. you don't do enough damage by x time, this happens)

For those who don't visit the link, he freezes time for 30+ seconds and stacks AOE attacks on the player the whole duration, then unfreezes and they trigger.

Another post about it: https://www.reddit.com/r/PathOfExile2/comments/1ju4efp/did_they_change_trialmaster_fight/