Bloodbag Imp Devil (boosted)

Devil's Sight. The imp's darkvision works in magical darkness.

Innate Spellcasting. The imp can cast the following spells, using Charisma as its spellcasting ability (save DC 11):

At will: detect evil and good, detect magic

1/day: vampiric touch

Magic Resistance. The imp has advantage on any saving throws it makes against spells and other magical effects  

Regeneration. The imp regains 4 HP at the start of each of its turns.

Transfusion. The imp can transfuse HP to another creature, if both are willing. At the end of each round in which both the imp and the other creature don't use actions or bonus actions and remain within 5 feet of each other, the imp takes 2 nonlethal damage (effectively reducing the number of HP it will regenerate on its next turn by 2) and the other creature regains 1 HP. The imp can't transfuse HP while incapacitated. Nothing prevents the imp from transfusing HP to multiple other creatures simultaneously, or another creature from benefitting from multiple bloodbag imps' transfusion simultaneously.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 3 (1d6) piercing damage, and the target must make a DC 16 Constitution saving throw against poison or tale a -1d4 reduction to its Strength (-2d4 if the attack was a crit). Whether it succeeds or fails, it must make this saving throw again one minute later. This Strength reduction can stack (and a creature reduced to 0 Strength automatically dies), and recovers at a rate of 2 points per day.

Invisibility. The imp magically turns invisible until it attacks, takes an action or a bonus action, takes damage, interacts with an object, or until its concentration ends (as if concentrating on a spell). Any equipment the imp wears or carries is invisible with it.

Shapechange. The imp can use its action to magically polymorph into a beast form that resembles a rat (speed 20 ft.), a raven (20 ft., fly 60 ft.), a spider (20 ft., climb 20 ft.), a goat (40 ft.), a boar (40 ft.), or back into its true form. Its statistics are the same in each form, except for the speed changes noted. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Wounding Curse (3/day). The imp targets a creature it can see within 30 feet of it and forces it to make a DC 11 Constitution saving throw or become cursed for 1 minute. While cursed in this way, whenever the cursed creature gets hit by a melee attack, it takes an extra 7 (2d6) necrotic damage, takes a stacking -1 to its Constitution (recovers at a rate of 2 points per day), and must make a DC 15 Constituion saving throw (it makes this saving throw before taking the -1 penalty) or become immune to healing (and can repeat the saving throw at the end of each of its turns to end the effect). Whether it succeeds or fails on this saving throw, the attack also opens a wound in its body. While wounded, at the start of each of its turns the creature takes 3 (1d4 + 1) necrotic damage for each such wound it has, and then makes a DC 15 Constituion saving throw, ending the effect of all such wounds affecting it. Alternatively, the wounded creature or another creature within 5 feet of it can spend an action in order to make a DC 15 medicine check to remove all wounds from the wounded creature, and receiving any healing (assuming the creature wasn't rendered immune to healing) removes all wounds as well. However, none of these methods prevent the accumulation of new wounds, as long as the creature remains cursed). A creature that succeeds on the initial saving throw against this curse becomes immune to it for 24 hours.