Devil's Sight. Magical darkness doesn't impede the devil's darkvision.
Magic Resistance. The devil has advantage on saving throws against spells and other magical effects.
Multiattack. The devil makes three melee attacks: two with its fork and one with its tail. It can use Hurl Flame in place of any melee attack.
Fork. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) piercing damage.
Tail. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 10 (1d8 + 6) piercing damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 17 Constitution saving throw or lose 10 (3d6) hit points at the start of each of its turns due to an infernal wound. Each time the devil hits the wounded target with this attack, the damage dealt by the wound increases by 10 (3d6). Any creature can take an action to stanch the wound with a successful DC 12 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.
Hurl Flame. Ranged Spell Attack: +7 to hit, range 150 ft., one target. Hit: 14 (4d6) fire damage. If the target is a flammable object that isn't being worn or carried, it also catches fire.
So these guys are the generic flying devils.
You know, the ones that show up by the thousands when a truly great hellgate opens.
CR11
Yeah, I think the material plane is royally F'd when a full-scale invasion happens.
fortunately they're preoccupied lol
Nope, because they aren't taking damage, they're just losing hitpoints. It would even bleed through temporary hitpoints.
revivify reanimates a dead person into the status of "living" once more, raise dead would animate the corpse into, effectively, a zombie. in the description of revivify:
"You touch a creature that has died within the last minute. That creature returns to life with 1 hit point. This spell can't return to life a creature that has died of old age, nor can it restore any missing body parts."
it'd be up to the dm's discretion as to weather the 1 hit point that heals the target also closes the wound, as it does state that it doesn't recover lost limbs (if you're using this spell, with the cost of the spell/ components, i'd give it to the party that it closes the wound(s) with that 1hp healed (in my opinion)).
but to answer the other half of your question, im sure the actual healing magic that restores hp will do the trick.