• Spellcasting. Othar is a 15th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 22, +14 to hit with spell attacks). Othar has the following wizard spells prepared: 
• Cantrips (at will): Mage Hand, Prestidigitation, Ray of Frost, Chill Touch, Toll the Dead
• 1st level (4 slots): Detect Magic, Magic Missile, Shield, Thunderwave 
• 2nd level (3 slots): Acid Arrow, Enlarge/Reduce, Scorching Ray
• 3rd level (3 slots): Counterspell, Dispell Magic, Fireball, Lightning Bolt, Haste
• 4th level (3 slots): Blight, Dimension Door, Greater Invisibility, 
• 5th level (3 slots): Cloud Kill, Dominate Person, Geas
• 6th level (2 slots): Chain Lightning, Disintegrate, Instant Summons
• 7th level (1 slot): Finger of Death, Simulacrum, Teleport
• 8th level (1 slot): Feeblemind

Multiattack. Othar makes 2 claw attacks, a tail attack, and a bite attack, or uses frightful presence and a bite attack.

Claw. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 32 (3d10 + 14) slashing damage.

Tail. Melee Weapon Attack: +16 to hit, reach 20ft,. one target. Hit: 26 (2d10 + 14) bludgeoning damage

Bite. Melee Weapon Attack: +16 to hit, reach 15ft,. one target. Hit: 38 (4d10 + 14) bludgeoning damage

Frightful Presence. Each creature of Othar's choice that is within 120 feet of Othar and aware of it must succeed on a DC 24 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Othars Frightful Presence for the next 24 hours. 

Brimstone Breath (Recharge 4-6). DC 26 vs Dexterity, line of 100ft, Hit: 80 (11d6 acid + 11d6 fire) Acid and fire damage

Claws: as a reaction when Othar is hit he can make a claw attack

Legendary Resistance (3/Day). If Othar fails a saving throw, he can choose to succeed instead.

Othar can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. Othar regains spent legendary actions at the start of its turn.

Bite Attack (Costs 1 action). Othar makes one bite attack.

Wing Attack (Costs 2 actions). Othar flaps his wings violently, any creature within 30ft of Othar must succeed on a DC 18 Dexterity saving throw or take 10d8 bludgeoning damage, pushed back 10 feet, and knocked prone.

Cast Spell (Costs 2 actions). Othar can cast a spell of 4th level or lower

Acidic Spit (Costs 3 actions). Othar spits a glob of acid onto a creature of his choice, the creature must make a DC 18 constitution saving throw, on a fail the creature takes 12d8 acid damage, and must continue to make the saving throw at the beginning of their next turn or take an additional 5d8 acid damage.