Tarnhem

When Tarnhem dies, it explodes, and each creature within 30 feet of it must make a DC 20 Dexterity saving throw, taking 70 (20d6) Fire damage on a failed save, or half as much damage on a successful one. The explosion ignites flammable objects in that area that aren't being worn or carried, and it destroys Tarnhem's weapons.

At the start of each of Tarnhem's turns, each creature within 5 feet of it takes 10 (3d6) Fire damage, and flammable objects in the aura that aren't being worn or carried ignite. A creature that touches Tarnhem or hits it with a melee attack while within 5 feet of it takes 10 (3d6) Fire damage.

Tarnhem has advantage on saving throws against spells and other magical effects.

Tarnhem's weapon attacks are magical.

Tarnhem makes two attacks: one with its longsword and one with its whip.

Melee Weapon Attack +14 to hit, reach 10 ft., one target. 21 (3d8 + 8) Slashing damage plus 13 (3d8) Lightning damage. If Tarnhem scores a critical hit, it rolls damage dice three times, instead of twice.

Melee Weapon Attack +14 to hit, reach 30 ft., one target. 15 (2d6 + 8) Slashing damage plus 10 (3d6) Fire damage, and the target must succeed on a DC 20 Strength saving throw or be pulled up to 25 feet toward Tarnhem.

Tarnhem magically teleports, along with any equipment it is wearing or carrying, up to 120 feet to an unoccupied space it can see.