Time-Warden

Ecology
Time-Wardens are celestial clockwork constructs, often taking the form of winged lions or sphinxes with bodies made of translucent, golden glass. They were created by the Argentari to guard their most chronologically sensitive artifacts. They exist slightly out of phase with the standard flow of time, making their movements appear blurred and erratic.
Lair Actions
In its sanctum, the Warden can use the following lair actions:
- Chrono-Shift: The Warden shifts the flow of time for all creatures in the room, causing a random effect (Haste, Slow, or Reverse).
- Temporal Banishment: A target is banished to a pocket dimension of frozen time for 1 round (DC 15 Charisma save).
- Echo-Summon: The Warden summons 1d4 "Echoes" of the players from a different timeline to attack them.
Combat Mechanics
The Warden can use a legendary action to "Rewind" its own HP to its starting amount once per battle. Its melee attacks deal force damage and can age the target by 1d10 years, potentially causing levels of exhaustion. It is immune to time-manipulation spells cast by others and can use Time Stop once per day.
Loot
The warden's core is the "Hourglass of Kings." This legendary item allows a user to cast Time Stop once; after use, the hourglass shatters into mundane sand.