How to save all companions in the House at the End of Time?

Solution 1:

Finally I've managed to save them all:

• Nok-Nok - apparently you can go "hero" or "jester" way, I've chosen the former. First killed the giant at Oleg's post, then let him keep the shrines. When he is challenged by the "king", you need to pass a test that will enrage the barghest and then kill it. You'll know that you've done it right if the goblins around you will start clapping. Afterwards, in your capital name Nok-Nok the official hero of your kingdom.
• Tristan - don't chase the escaping cultists, when you have to choose his fate, tell him to stay mortal, save the final sacrifice. Apparently it helps to bring Jaethal to the last quest (dealing with the last cultists)
• Jaethal - I let the undead girl die, I didn't take the hag's deal but I've sided with Jaethal against her killer. When meeting with her daughter, I've managed to convince Jaethal to spare her (bringing Tristan to this mission helps). Jaethal exploded but returned in the House.