Large Dragon (Metallic), Chaotic Good
Actions
Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of Slowing Breath.
Rend. Melee Attack Roll: +7, reach 10 ft. Hit: 15 (2d10 + 4) Slashing damage.
Acid Breath (Recharge 5-6). Dexterity Saving Throw: DC 14, each creature in a 40-foot-long, 5-foot-wide Line. Failure: 40 (9d8) Acid damage. Success: Half damage.
Slowing Breath. Constitution Saving Throw: DC 14, each creature in a 30-foot Cone. Failure: The target can't take Reactions; its Speed is halved; and it can take either an action or a Bonus Action on its turn, not both. This effect lasts until the end of its next turn.
Found on p.78 of MM2025 (Free Rules)