Keen Smell. The displacer panther has advantage on Wisdom (Perception) checks that rely on smell.
Pounce. If the displacer panther moves at least 20 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 12 Strength saving throw or be knocked prone. If the target is prone, the panther can make one bite attack against it as a bonus action.
Avoidance. If the displacer panther is subjected to an effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.
Lesser Displacement. The displacer panther projects a magical illusion that makes it appear to be standing near its actual location, causing attack rolls against it to have disadvantage. If it takes any damage, this trait is disrupted until the end of its 1d4 turns. this trait is also disrupted while the displacer beast is incapacitated or has speed of 0. 

Multiattack. The displacer panther can make two attacks with its tentacles.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage.
Claw. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage.
Tentacle. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 5 (1d4 + 3) bludgeoning damage plus 2 (1d4) piercing damage.