When a demon overcomes a Contain, the Contain is destroyed. I believe this clarifies all your problems with the two demons and the Contain.
Yes, this clarify a lot the Contain situation.
If both Igriph and Damien fail, the only way the Sorcerers have to allow them to pass is to physically destroy the barrier (the wall in this case), or they can try to change or delete the contain using Lore?
The sorcerers cannot challenge the Contain as if they were demons. They can use Lore rolls (against the Contain, i.e., the sorceress' defensive roll) to modify their attempt to destroy the door.
But why you are obsessing about this when the demon has a Power of fucking 13, I do not understand. If its Stamina is 12, it can rip that door apart. Why are you bothering me with this nonsense?
Because even if probably Igriph will have no trouble in breaking down the contain, there is still a noticeable chance that he will lose the roll (around 22% by my calculations, not considering possible bonus dice or penalties), and there is a 8% chance that BOTH demons will fail to break through. Small, but still that number make me wish to be able to answer the players questions if that happen (I am the player that made a 1% chance roll to call for divine intervention in D&D, after all, ruining "the GM's story" for a while...). Being able to bring down the contain WITHOUT bringing down the wall make a really big difference in that situation (it means they can do it from the outside, where their demon still can defend them if attacked.
What I was thinking, and what I was asking, was something more on the type "with my knowledge of sorcery, I know how to remove this contain spell from this door, all I have to do is write these countering runes exactly here and here with chalk and blood" but what you say is interesting too: so a Sorcerer can, with a Lore roll against the Contain strength, tell the demon "a different way" different enough to allow it another roll to break the contain? How it works, telling that is an action? (so one action for the roll, one action to tell the demon, one action for the demon to try again to enter) and it needs to be a different attempt in the fiction ("now try closing your eyes and going backwards" ) or not?
… in the meantime, between the death of the host and the hop, no physical attack of any kind can hurt the demon (a mental attack with psychic force could, if the user is able to perceive the disembodied spirit of the demon). I don't think I need to add any new power to get this, it's simply a matter of "to be able to kill it you have to be able to attack it", am I right?
No. The ability is well-conceived but it is not free. You are adding a significant ability for free by cheating. It is very difficult to talk about this game with you because both you and the players seem to want to cheat, very badly, at all times. Peter is not and cannot ever be immune to attack; that is cheating. No demon is ever free from the rule that a demon is at all times a "person" in mechanics terms except where its abilities alter that template. Being outside a host body does not sidestep that rule.
The best you can do to get this effect is for Peter to have Cloak, defined as "invisible outside a host." There is no real "disembodied" in Sorcerer, but Cloak and the Armor it already has will provide the feature you want. Given Peter's Power, that should work very well.
Ah, but Peter already had cloak ("Peter, the assassin possessor with hop, range, cloak and perception") exactly for that reason, to avoid being seen when it enter or leaves host bodies. The fictional description of the cloak effect is "disembodied invisible spirit" more than simply "invisible" tough...
The way I imagine Peter, it can be hurt in two ways: using the host (hurting the host pass some of the hurting to Peter - but the death of the host sever this connection) or directly (but to hurt it directly, you have to be able to directly perceive Peter). To hurt it directly you have to use a form of attack able to "hit a spirit" (psychic force, or some sort of special attack - for example the demonic guns used by Damian are able to hurt it, but a normal gun would not. Igriph's scorpion tail sting could, Isabella's fist could not).
This is the sticky point: you have to be able to perceive it (making your roll against cloak) AND use a psychic or special attack to be able to hurt Peter "between hosts". This is allowable by the rules, or if someone is able to perceive Peter at that point, is able to attack it with a normal gun too, and the Armor at most can shift the damage to the fist table?
Having a hopping possessor demon and a Sorcerer currently at zero humanity (being hit by a taint) cause another question: if the demon possess the sorcerer, does this mean that the Sorcerer consciousness is destroyed, or the demon victories have to be more than the "untainted" humanity for that to happen? What about NPC Sorcerers that are at zero humanity?
The tainted person will roll a single die and the demon will get a bonus die. That should have been obvious. NPC or PC makes no difference at all.
This answer confuse me. Probably it's better I repeat the question using the concrete numbers.
Peter is hopping. In the room there is Alessandro, a PC with stamina and humanity both at 2. At this moment Alessandro is under the effect of a taint from Abaddon, the other demon bound by Selene (a parasite) and his current humanity is at zero. (fictionally, he is under Abaddon's control. Not like a puppet, he still act independently, but he obey automatically any of the demon's suggestions - it's what happen to zero-humanity sorcerers here, they become in practice slaves of their demons. The effect of the taint stop when he is no longer in Abaddon's presence or at dawn, the one that come earlier)
The roll to take Alessandro as host is Peter's Power vs Alessandro's Stamina (not humanity), BUT, if the number of victories is greater than the host's humanity, the host personality dies forever.
There is no roll against humanity here (at least, not in the manual), no roll against zero dice. There is a roll against stamina (2), and... even if the roll is won with a SINGLE VICTORY, it's still greater than Alessandro current humanity (zero). So at the end of the roll, Alessandro ha only two possible states: (1) alive and unpossessed (if he won the roll) or (2) possessed and dead.
This, if the humanity value to consider is the current one. But if, instead, we use the "untainted" value of humanity (2) to compare to the demon's victories, after the roll Alessandro has three possible states:
(1) alive and unpossessed (if he won the roll) or (2) possessed and dead, if the demon won with 3 or more victories, or (3) possessed, but Alessandro remains "as a flickering bit of consciousness barely hanging on" if the demon won the roll with 1 or 2 victories.
What is the value to consider, "current" or "untainted"?
Y rolls only one die for a Stamina action, AND X has a 2-dice bonus to his attack roll against B, right?
That's not automatic. It only applies if X's new action flowed from the prior action. "I hit him again" is definitely not enough to establish that flow. It is not "almost a given" – it is a defined game mechanic with very specific requirements and those requirements have to be met. Specifically the player has to say something that makes that flow/connection apparent. You are trying to be the player, a distinctive fault which arises directly from the play-experience you described so well above. This is a fault and you should stop it.
Let's use again a concrete example:
The player says "I hit him with my fist", we roll, the player has the higher roll, I abort my action to roll again, I lose again, the player has one victory, so automatically this give me a 2 points penalty on stamina (and will, lore, etc.), of which 1 is only for the next roll and the other is lasting.
After this, we declare actions again, and the players says "I hit him again, so I add the two victories to my roll, right?", and I answer "no, saying that you hit him again is not enough to get the roll-over victories as bonus dice. You have to say something that make that flow/connection apparent" (I would probably say "evident")
The player asks "like what? Give me an example"
So, of these, what would be enough?
A) "I take advantage of him still reeling from my blow to hit him again" [citing the previous action as the reason he is able to do that at all, this I think qualify, the other options are less clear]
B) "After hitting him with my right, now I swing at him with my left" [narrating the two actions as a linear continuous narrative]
C) "I press my advantage hitting him again" [as the first version but with less details]
D) "I say 'don't go down with a single blow, I have another one for you' and hit him again" [simply citing the previous action in character dialogue]
E) other cases?