Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of Time-Warping Breath.
Rend. Melee Attack Roll: +7, reach 10 ft. Hit:14 (3d6 + 4) Slashing damage plus 7 (2d6) Necrotic damage.
Ruinous Breath (Recharge 5–6). Constitution Saving Throw: DC 15, each creature in a 30-foot Cone. Failure: 36 (8d8) Necrotic damage. Success: Half damage.
Time-Warping Breath. Wisdom Saving Throw: DC 15, each creature that isn't currently affected by this breath in a 30-foot Cone. Failure: The target's Speed is halved, it can't take Reactions, and it can take either an action or a Bonus Action on its turn, not both. It repeats the save at the end of each of its turns, ending the effect on itself on a success. After 1 minute, it succeeds automatically.
Draconic Scions of an Ancient Empire