Well then, a quite interesting concept.. let's see based on our current skill-sets, I'd say first to get murdered is most likely Aideen. He has little to no combat ability compared to most here, but tends to wander off alone at times, sorry. The helpless victim would be Pandora because no one would try and help her as there would be little to no obligation to do so. Aravind or possibly Freya would most likely snap and kill themselves and I believe Kirsi would be most likely to snap and kill someone else. Saori would be killed in a creative way I believe the murderer would like to drag it out as much as possible. Nova would have the least remorse of killing us all I feel, or if pushed too far possibly Aderyn. Whoever of the two wasn't the murderer would be the accomplice and honestly, I don't think there would be any survivors aside from Ikki as he can't really be killed.