Buffosneryx

Heated Body. A creature that touches Buffosneryx or hits her with a melee attack while within 5 feet of her takes 10 (3d6) fire damage.

Multiattack. Buffosneryx makes two attacks with her Snatching Claws and one with her Vicious Jaws. She can use her Devour the Weak in place of her Vicious Jaws.

Infernal Inferno. Ranged Weapon Attack: +11 to hit, reach 60 ft., 3 targets. Hit: 21 (4d6 + 6) fire damage.

Infernal Tail Drill (Recharge 5-6). Melee Weapon Attack: +14 to hit, reach 15 ft., 1 target. Hit: 51 (8d10 + 8) piercing damage plus 14 (4d6) fire damage. If the target is a creature and is reduced to 0 hit points by this attack, they die instantly.

Snatching Claws. Melee Weapon Attack: +14 to hit, reach 10 ft., 1 target. Hit: 18 (3d6 + 8) slashing damage. If the target is a large or smaller creature, it must make a DC 17 Dexterity Saving throw or be grappled. 

Vicious Jaws. Melee Weapon Attack: +14 to hit, reach 10 ft., 1 target. Hit: 25 (4d8 + 8) Piercing damage plus 7 (2d6) fire damage. If the target is a large or smaller creature, it is grappled (Escape DC 17). Until this grapple end, the target is restrained and Buffosneryx can't bite another target.

Coil. Melee Weapon Attack: +14 to hit, reach 10 ft., 1 target. Hit: 21 (3d8 + 8) bludgeoning damage plus 5 (1d8) fire damage. If the target is a large or smaller creature, it is grappled (Escape DC 17). Until this grapple end, the target is restrained and Buffosneryx can't coil another target.

Devour the Weak. Buffosneryx makes one bite attack against a Large or smaller creature she is grappling. If the attack hits, the target takes the bite’s damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside Buffosneryx, and it takes 35 (10d6) fire damage at the start of each of Buffosneryx's turns.

If Buffosneryx takes 45 damage or more on a single turn from a creature inside her, Buffosneryx must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of Buffosneryx. If Buffosneryx dies, a swallowed creature is no longer restrained by her and can escape from the corpse by using 10 feet of movement, exiting prone.

Spellcasting. Buffosneryx's innate spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). She can cast the following spells requiring no material components:

At will: Fire Bolt, Heat Metal

3/day each: Hellish Rebuke (3rd level), Counterspell, Fireball

2/day: Wall of Fire,  Immolation

1/day: Fire Storm

Channel the Warpath.  As a bonus action, Buffosneryx can focus on one of two Strength of the Warpath runes, increasing her strength score by 2 for 10 minutes (up to a total of 30). After the 10 minutes, Buffosneryx must wait another 10 minutes before activating that rune again.

Fire of the Warpath (2/day). Engulfing herself in flames as a bonus action, any entity within 20 feet of Buffosneryx must make a DC 20 Dexterity saving throw, taking 14 (4d6) fire damage on a failed save or half as much on a success. Buffosneryx then gains 30 temporary hit points and has advantage on the next Strength check or attack. For one minute, Buffosneryx's melee attacks do an additional 2d6 fire damage on a hit.

Buffosneryx 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. Buffosneryx regains spent legendary actions at the start of its turn.

Snatch. Buffosneryx makes a Snatching Claws or Coil attack.

Blazing Inferno (Costs 2 Actions). Buffosneryx makes an Infernal Inferno attack.

Overheated Engine (Cost 3 Actions). Buffosneryx recharges their Infernal Tail Drill and uses it. This can only be done if Fire of the Warpath was used on their last turn.