Sources
CR
Type
Size
Alignment
Movement

Adult Time Dragon

Huge Dragon, Neutral

Armor Class 19 (natural armor)
Hit Points 250 (20d12 + 120)
Speed 40 ft., fly 80 ft., climb 40 ft.
STR
25
+7
DEX
14
+2
CON
23
+6
INT
23
+6
WIS
16
+3
CHA
20
+5
Saving Throws DEX +8, CON +12, WIS +9, CHA +11
Skills Arcana +12, History +18, Perception +15, Stealth +14
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 25
Languages all
Challenge 18 (20,000 XP)

Traits

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Actions

Multiattack. The dragon makes three Rend attacks.

Rend. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit:14 (2d6 + 7) slashing damage plus 7 (2d6) force damage.

Time Breath (Recharge 5–6). The dragon exhales a wave of shimmering light in a 60-foot cone. Nonmagical objects and vegetation in that area that aren't being worn or carried crumble to dust. Each creature in that area must make a DC 20 Constitution saving throw. On a failed save, a creature takes 36 (8d8) force damage and is magically weakened as it is desynchronized from the time stream. While the creature is in this state, attack rolls against it have advantage, and it has the poisoned condition. On a successful save, a creature takes half as much damage only. A weakened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself after it succeeds on three of these saves.

Reactions

Reactive Rend. After using Legendary Resistance or in response to being hit by an attack roll, the dragon makes one Rend attack.

Slow Time. Immediately after a creature the dragon can see ends its turn, the dragon targets a creature it can see within 60 feet of itself that is weakened by its Time Breath. Until the weakened effect ends on the target, its speed becomes 0, and its speed can't increase.

Time Slip. The dragon halves the damage it takes from an attack made against it, provided it can see the attacker. The dragon can then immediately teleport, along with any equipment it is wearing or carrying, up to 30 feet to an unoccupied space it can see.

Lore

These sleek dragons harness the power of time to manipulate the past, present, and future. Time dragon wyrmlings are born with shining scales and have horns that are barely more than nubs. As they master the flow of time, their horns grow with branching, rainbow-hued veins suggestive of time's paths and possibilities. Ancient time dragons can create temporal gates connected to specific times and places in the multiverse. Using these, they and allied creatures can travel anywhere in time to…