Stealth attack (no ontology)
From Mazeworld
Performing a stealth shot is one of the contestant's abilities.
A contestant needs to have taken cover successfully, so his/her enemy did not notice him/her, and own a weapon equipped with a silencer. If the contestant met both of those requirements, he/she can attempt a stealth shot.
Using a silenced weapon, the contestant can attempt shooting at his/her foe from behind her cover, and remain stealthy. The enemy is likely to hear (and be hurt) by the shot, but will not know where the shot came from, until the contestant busts his/her cover or uses a weapon that isn't silenced. This can be useful as even if the contestant misses his/her shot, he/she will remain hidden and the encounter is likely to not attack.
Non-firearms: It is possible to use the techniques described above to attempt a stealth kill with a melee weapon, such as with a knife, or the piano wire which can only be used that way. It is noticeably riskier, as if dice are against the contestant, he/she will be noticed and the foe will attack. On the other hand, if successful, the attack is likely to immediately kill.