I'm running the House of Dust and Ash adventure from the discipines of dark gods and introduced a new player to the adventure once my existing group got to Solomon. So i have a group of 6 players, this is not the issue however.

My problem is now twofold, Firstly in the last round of combat with the Wreckers the psyker in the group rolled perils and turned into a unbound deamonhost.

This has left me with a few problems, he has decided not to burn a fate point to ignore the peril (something i will check with him before the next session), so how do i deal with an unbound deamonhost not ripping my group apart without it seeming like they are getting off easy, i was going to go for a round or two of combat before having it disappear into the warp to become a villian later. If my player burns the fate point this post is null and void.

Secondly, how do I introduce a new character into the party on the Isle, other than making him from a different inquisitor but that would then remove him from the group after the adventure is concluded. I know he could always be a freelance agent that the other plaers recruit to help them, but my players cell seems to becoming very insular and not trusting anyone not even their inquisitor.

Thanks for your thoughts

Your problem is simple.

As you start to talk to the "I will not born a FP"-Player, open up with

(you)"So, what is the concept of your new character? It would be good if it would be somethinig scummy or a PDF-Soldier or an Adept. These are the types the others could believeablly recruit on the island´"

(player) "Hey... wait! I intended to to play the Daemonhost as my pc!"

(you): *mildly laughing* Of course not! A pc that is taken over by a daemon turns to an npc. Same as your character would achieve 100 CP or IP. If you want to keep your Psyker, you need to burn the FP. Otherwise, the other players would need to overwhelm the npc Daemonhost and secure it long enough so it can be exorcised. And trust me, this will not happen.

Simply, be firm in that points. After some whining, your player will burn the FP...or you will have a new nice fight (for which the other players will hate the moron) and you have an pc in your group...

IF your player really wants to loose his psyker (for some reason or the other),
sources for other PC are

Those criminals from "Deadtown". Anything with a slighty shoody background and
a more "for hire" stance should do.

An Adept or Guardsman in the House itself could side with the pc as the carnage begins
You would simply need to tell the pc that his pc had to keep himself in the background
"till a certain point at the auction. You won´t miss it, trust me!"

Anything that could have travelled with Rupio. As push comes to shove, the pc
decides that hanging on to this fob will not do him good. No matter how handsome, rich
and/or well paying he is...

Valdek said:

You do nothing other than run the damon host as you see fit. Should it attack the rest of the group proceed with combat till a character has to Burn a Fate Point to live then have that Player pray to the Emperor and cast the daemon back into warp.

Valdek said:

Should the Daemon Host attack the party and if the party is injured while the characters recover from their wounds reinforcements could be sent by the Inquisitor.

If the Inquisitor is a psyker himself he might have had a vision and have sent reinforcements.

Maybe the characters actions/paranioa/distrust has concerned the Inquisitor enough so to send agents to assess the other characters or something along those lines.

Have everyone somehow get knocked out, waking up a bit later. Abbot Tamas will probably have "dealt" with the being in some way. Have the ship be sufficiently damaged/scorched on the inside, kill alot of the passengers/crew. The wrecker ship possibly collided more completely, and is a total mess on the inside. Have them arrive a day late. If a new character needs to be introduced, I would say having another acolyte that arrived on another ship is acceptable. Just have them bear a seal of the party's inquisitor. Its entirely possible for an inquisitor to not inform acolytes of other groups or acolytes. Besides, the party shouldn't object that much (they lost a guy in perhaps the most terrifying manner).

In hindsight, you probably should roll perils hidden from the party.

Also, while I certainly am not against allowing a player to burn a FP to stop this (it falls under the burn to not die), Psychic Phenomena/Perils of the warp is not a test, and thus cannot benefit from the use of fate points. Just a side thing. Once again, the GM should roll on that table, as alot of those can just plain break the game (oh, you fall up for 15 seconds. Thats a TPK).

Don't let him off too easy! Punish the evil Psyker!

If he chooses to burn a Fate Point to survive the whole Daemonhost event, be sure to still give him all the Corruption Points it brings

Thanks for the advice so far, as for rolling perils i allow my psyker player to do that he is the most versed in the 40k universe out of the players. He knew full the risks of using his powers and to some degree has been joking looking foward to it. If he does spend the FP he will get the corruption points for 'Surviviing' being a deamonhost don't worry about that.

As for exorcising him, it's not going to happen as he is the only one in the group wth the relevant lore skills to perform anything close however my witch hating guardsmen now has more of a reason just to execute every psyker he sees............fun.

I guess there's lots of opportunities to bring new PCs into the group when finally arriving on the Burning Isle.

First and foremost, the new character could be one of Silas Marr's acolytes who has been sent to the isle when the whole auctioning administration was set up. Remeber that Marr is a liar and trickster by heart - he wouldn't necessarily have told your group about all his agents and servants.

The 'new guy' could also be recruited by your group of acolytes when everything goes downhill right from the arrival. He might be a more or less courageous guardsman, a sailor from one of the skyships, an adept or one of Captain Rubio's henchmen who just clings to the group for dear survival. That being the case, he obviously wouldn't be a servant of the Inquisition yet. But hey, in my book Silas Marr is constantly hiring to make up for the losses...

Thankyou for all your replies and help, I have now finished running the house of dust and ash, bloody players (he looks tough and in charge, let hunt the @$$ down, 1 hour into the countdown and out).

I managed to drop the new assassin in, in deadtown, sent on another ship to shadow the cell, and intervene if necessary. The gaurdsman of the group is a little narrowminded to the 40k universe (for the inquisitor in a good way), he's a hitty character that defaults to kill it first, kill it second, kill it some more and then when everything is dead go looking for some more stuff to kill, but track down a heretic, nahhhhhhh just kill them all.

I used Rubio to introduce a Scum character to the group, a very charismatic character, so with some good background from the player, was there using Rubio to get a look at the wares to see what they were, who bought them so he knew who to rip off later.