Excal-heim
Undead Fortitude.
If damage reduces Barney to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit.
On a success, barney drops to 1 hit point instead.
Undead Nature.
Barney doesn't require air, food, drink, or sleep.
Multiattack.
Barney makes two attacks: one with its bite and one with its tail.
It can't make both attacks against the same target.
Bite.
Melee Weapon Attack: +10 to hit, reach 10 ft., one target.
Hit: 33 4d12+7 piercing damage.
If the target is a Medium or smaller creature, it is grappled (escape DC 17).
Until this grapple ends Barney can't bite another target.
Tail.
Melee Weapon Attack: +10 to hit, reach 10 ft., one target.
Hit: 20 3d8+7 bludgeoning damage.