Can I boost a friend with Trial of Chaos?

Hi!

I have a friend who will need help for 4th Ascendancy.

Have tried inviting him to Trial of Sekhemas, but it failed (maybe because I had been using CI) and that 4 floor Trial is so long and not always ended up with enough Honor for Final Boss.

Is there a way to safely help him in Trial of Chaos (Sanctum one)? We tried inviting him before and after 10th room Boss, before and after TrialMaster
Simple being there at start will port him to fights (Arena) and if he is not careful killed. After he ported to Hideout then can not port back at all.

Thank you,
Kobor