Alchocodon

Aging Aura. Any creature that starts its turn within 30 feet of the Alchocodon must make a DC 19 Constitution saving throw. On a failed save, the creature ages 1d8 years. A successful save renders the creature immune to this effect for 24 hours. If this aging causes a creature's age to exceed its natural lifespan, it dies instantly.

Timeless Insight. The Alchocodon can foresee events up to one minute into the future. It has advantage on attack rolls, saving throws, and ability checks, and attacks against it have disadvantage. However, creatures with Spell Sniper can make spell attacks against it without disadvantage.

Temporal Displacement (Recharge 5-6). The Alchocodon can touch a creature within 10 feet and shift it out of time. The target must succeed on a DC 19 Wisdom saving throw or be removed from the timeline for 1 minute. While removed, the creature is incapacitated and can't be targeted by any attack, spell, or other effect and can't be affected by spells or effects except Alchocodon's Temporal Wrath. At the end of the minute, the creature reappears in the space it left or the nearest unoccupied space if that space is occupied.

Multiattack. The Alchocodon makes three Celestial Staff attacks.

Celestial Staff. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) radiant damage and the target must make a DC 19 Wisdom saving throw or its hit point maximum is reduced by 6. This reduction lasts until the target finishes a long rest or time travels. The target dies if this effect reduces its hit points maximum to 0.

Temporal Wrath (Recharge 5-6). The Alchocodon releases a burst of temporal energy in a 60-foot radius. Each creature in that area must make a DC 19 Constitution saving throw. On a failed save, a creature takes 45 (10d8) radiant damage and ages 1d20 years. On a successful save, it takes half as much damage and doesn't age. Creatures that have been shifted out of time by the Temporal Displacement ability take half damage and don't age from this attack. Plants wither in the attack area, and all water sources not being carried evaporate.

Temporal Paradox. When the Alchocodon is hit by an attack, it can use its reaction to force the attacker to make a DC 19 Intelligence saving throw. On a failed save, the attacker is confused for 1 minute (as per the confusion spell). The attacker can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Time Leash. When a creature or group of creatures attempts to time travel while within 60 feet of the Alchocodon, it can use its reaction to time travel to the exact same time and location as those creatures.

The Alchocodon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time but can be used at the end of any creature's turn. The Alchocodon regains spent legendary actions at the start of its turn.

Chrono Step. The Alchocodon moves up to its speed without provoking opportunity attacks.

Gaze of Eternity (Costs 2 Actions): The Alchocodon targets one creature it can see within 60 feet. The target must succeed on a DC 19 Wisdom saving throw or it drops everything it is holding and is stunned until the end of its next turn.

Time Reversal (Costs 3 Actions): The Alchocodon reverses time for one creature it can see within 60 feet. The target must succeed on a DC 19 Charisma saving throw or it is moved back to the position it was in at the start of its last turn. All damage and conditions it received since then are undone.