Monocular Illusion Resistance. The  chief has advantage on saving throws against illusions that include visual elements it can see.

Poor Depth Perception. The chief has disadvantage on any attack roll against a target more than 5 feet away.

Multiattack. The chief makes three attacks: two with its claws and one with its bite; or it makes two attacks with its glaive or javelins.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 12(2d6+5) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8(1d6+5) slashing damage.

Glaive. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 16(2d10+5) slashing damage. 

Javelin. Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft.  or range 30/120 ft., one target. Hit: 12 (2d6+5) piercing damage.

Aggressive. As a bonus action, the chief can move up to its speed toward a hostile creature that it can see.

Hypnotic Stare.  The chief clops stares at a single individual up to 60 feet away, who must make a DC 13 Wisdom roll or be charmed for one minute. While charmed by this spell, the creature is incapacitated and has a speed of 0. The condition ends for an affected creature if it takes any damage or if someone else uses an action to shake the creature out of its stupor. A target that successfully saves is immune to this cyclops's stare for the next 24 hours.