Argamus

Spellcasting. Agamus is a 5th-level spellcaster. Its spellcasting ability is intelligence, spell save DC 30, +20 to hit with spell attacks). The [monster name] has sorcerer and wizard spell lists prepared:

Cantrips (at will): Ray of Frost, Eldritch Blast, Fire Bolt, Poison Spray, Acid Splash              1st level (6 slots): Chromatic Orb, Magic Missile, Shield, Thunderwave, Sleep, Witch Bolt 2nd level (5 slots): Cloud of Daggers, Gust of Wind, Invisibility, Scorching Ray, Web            3rd level (4): Fireball, Lightning Bolt, Daylight, Water Walk 

Bite. Melee Weapon Attack: +4 to hit, reach 6 ft., 1 target. Hit: 28 (2#12 + 4) piercing damage.

Claw. Melee Weapon Attack: +6 to hit, reach 8 ft., 1 target. Hit: 30 (2d12 + 6) slashing damage.

Frosty Death Breath. Ranged Weapon Attack: +8 to hit, range 50/100 ft., 5 targets. Hit: 80 (12d6 + 8) cold damage.

Frosty BOOM! (Costs 5 Actions).  Agamus causes five huge explosions of ice shards and cold magic. Anything within 5 feet of an explosion takes 5d4 piercing damage and 3d6 cold damage