Dear all,
I again need some advices to decide how to proceed with my group.
We just finished Tattered Fates and in the climatic end-scene the clash between the Beloved and the Widower was sort of won by the Widower when he cut down the Beloved after a couple of rounds of close combat. My players did not intervene into the duel beforehand, partly due to being busy defending against other assailants and saving Julia Strophes and partly due to being rather undecided who to kill and who to support.
So when the Beloved ran out of Precognitive Dodges (I used the stats of the False Prophetess from DotDG with a couple Divination Powers and Hellish Blast) and was cut down by the Widower, he turned upon the PCs who tried to shot him or manipulate/destroy the Steel Clock (they haven’t gotten the hint that the keystone is the, well, key part of it). First he cut down the Psyker hammering onto the Steel Clock without taking a sweat and then he proceeded to attack and cut down a major NPC as well as raining blows upon the groups Arbitrator. After a second round of Defensive Stance the Arbitrator suffered two criticals and went down in a pirouette. The groups Assassin (scion of Haarlock) further tried to somehow destroy the keystone or stop the mechanism of the Steel Clock) and the Tech Priest, who just had helped Julia Strophes (who tried to claw her eyes out) to the exit, kept firing his Fury Laspistol at the laughing Widower without notable effect.
In the meantime the groups Guardsman had left his firing position, rushed to the body of the Beloved, after he had plundered three corpses on the way (…), and picked up his vile Daemon Sword. He won the Daemonic Mastery test (i.e. opposed WP-test vs. Astral Spectre) and charged the Widower for 24 damage (!) in the first round and 31 damage (!!) in the second round (single strike) thereby destroying the Widower (31-10=21 i.e. a single wound more than needed) utterly.
Almost directly afterwards, the rest of the group was threatened by a group of four armed people led by a Bolt Pistol wielding woman. This is in fact another Acolyte group of the groups Inquistor, that is hunting for the group, as they had disappeared (abduction at the start of TF) and the Inquisitor fears that they had became rogue elements or renegades or whatever.
To cut a long story short, I am not sure how to handle this whole Daemon Sword thingy. While I always wanted to tempt my players with radicalism in the near future, this incident somehow handed this opportunity suddenly on a silver platter and left me a little overwhelmed. Using Chaos (or its weapons) in a desperate situation for the sake of surviving (not only of oneself, but of a whole planet) and overcoming a highly destructive foe through it sounds just like good old Eisenhorn. So how shall I proceed to keep it interesting and the damnation palpable without going “lol, D100 Corruption Points and spontaneous mass mutation et al.”? Any ideas?
Thanks in advance!

