Blind. SCP-939 suffers from blindness at all times.
Hearing. SCP-939 turns all area within 30 feet of it into difficult terrain, creatures can choose to ignore this difficult terrain, but reveal their location to SCP-939. Actions that would reasonably result in noise give away locations to SCP-939, however it is easily distracted by throwing a loud object.

Ultrasensitive. If SCP-939 hears an especially loud sound, it is deafened for 3 turns.

Mimicry. SCP-939 can mimic things it hears, if an NPC is not in sight, and the luring 939 is not in sight, the DM can choose to place the minifigure or icon of the NPC at SCP-939's location, tricking the players into believing it is there.

Amnestic Gas. SCP-939 can lay down a 15 foot sphere of amnestic gas, SCP-939 is invisible to those inside this gas, unless it attacks, or is damaged, creatures inside the field perform all actions at disadvantage.

Bite. Melee Attack: +2 to hit, reach 5 ft., 1 target. Hit: 4 (1d6 + 1) Piercing damage, prevents the inflicted from using an item for 2 turns.

Slash. Melee Attack: +1 to hit, reach 5 ft., 1 target. Hit: 4 (1d6) Slashing damage.

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Uncaring dash. SCP-939 can triple it's move speed upon hearing a noise, but give up it's Ultrasensitive trait.