Please help with ideas to buff Banshee

[Mordna]

I love this creature and my group has a (hilarious) history already with it from lower levels. I would love to revisit it again, but I would like it to be like a mini-boss for level 12 characters. I would welcome anyone's ideas on how to make the Banshee more badass and CR appropriate. Thank you.

Please find below the Banshee's official stats to go from:

Banshee
Medium undead, chaotic evil

Armor Class 12
Hit Points 58 (13d8)
Speed 0 ft., fly 40 ft. (hover)

STR 1 (-5) DEX 14 (+2) CON 10 (+0) INT 12 (+1) WIS 11 (+0) CHA 17 (+3)

Saving Throws Wis +2, Cha +5
Damage Resistances acid, fire, lightning, thunder; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities cold, necrotic, poison
Condition Immunities charmed, exhaustion, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained
Senses darkvision 60 ft., passive Perception 10
Languages Common, Elvish
Challenge 4 (1100 XP)

Detect Life. The banshee can magically sense the presence of creatures up to 5 miles away that aren't undead or constructs. She knows the general direction they're in but not their exact locations.

Incorporeal Movement. The banshee can move through other creatures and objects as if they were difficult terrain. She takes 5 (1d10) force damage if she ends her turn inside an object.

ACTIONS
Corrupting Touch. Melee Spell Attack: +4 to hit, reach 5 ft., one target. Hit: 12 (3d6 + 2) necrotic damage.

Horrifying Visage. Each non-undead creature within 60 feet of the banshee that can see her must succeed on a DC 13 Wisdom saving throw or be frightened for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, with disadvantage if the banshee is within line of sight, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to the banshee's Horrifying Visage for the next 24 hours.

Wail (1/Day). The banshee releases a mournful wail, provided that she isn't in sunlight. This wail has no effect on constructs and undead. All other creatures within 30 feet of her that can hear her must make a DC 13 Constitution saving throw. On a failure, a creature drops to 0 hit points. On a success, a creature takes 10 (3d6) psychic damage.

[Brutalitops]

One simple Idea is to give it 2 more attacks and up the DC to 16. Toss in a regeneration affect that is negated by sunlight or radiant damage and give it access to a few necromancy spells such as Horrid Wilting which does 12d8 necrotic damage and the harm spell which does 14d6 but cannot reduce the target below one hit point

Have its frightening gaze which fears people be usable with its multiattack. Remember to give it minions like spectors shadows or wraiths which you can easily flavour as the souls of its victims by giving it a form of create undead usable on people it kills.

Also you should have walls in the dungeon so it can move in and out to attack people. Also give it an aura that deals 5 necrotic damage to people around it to make the players fear it or give it a once per day reaction ability that turns healing energy in harmful energy and makes a creature take damage when they are healed equal to the amount healed once per day.

If the players are level 12 they should be able to handle a banshee like this. And remember to make the wail ability recharge on a six not a once per day ability

Don't forget legendary resistances or actions or the monster will get turned in the first round

[miniatureaddict]

Raise the ac
Make her resistant to all weapons (Except silvered weapons)
Double hit points.
Give her ghoul minions
Heck just give her a mace of terror.

[Mordna]

Thank you both for your ideas and advice!

Here is what I got.
I took the Harm spell and made it an option for a legendary action. Took the regeneration from the vampire. Legendary resistance, turn resistance both in. Doubled the HP and raised the AC. Did I miss anything? Any changes you'd make?
IS CR 13 fair XP-wise?

Banshee Princess
Medium undead, chaotic evil

Armor Class 18
Hit Points 117 (26 d8)
Speed 0 ft., fly 40 ft. (hover)

Saving Throws WIS +2, CHA +5
Damage Resistances acid, fire, lightning, thunder; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities cold, necrotic, poison
Condition Immunities charmed, exhaustion, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained
Senses darkvision 60 ft., Passive Perception 10
Languages Common, Elvish
Challenge 13 (10000 XP)

Detect Life: The banshee can magically sense the presence of creatures up to 5 miles away that aren't undead or constructs. She knows the general direction they're in but not their exact locations.

Incorporeal Movement: The banshee can move through other creatures and objects as if they were difficult terrain. She takes 5 (1d10) force damage if she ends her turn inside an object.

Legendary Resistance: If the banshee fails a saving throw, it can choose to succeed instead. (3/Day)

Turn Resistance: The lich has advantage on saving throws against any effect that turns undead.

Regeneration: The banshee regains 20 hit points at the start of its turn if it has at least 1 hit point and isn't in sunlight or running water. If the banshee takes radiant damage or damage from holy water, this trait doesn't function at the start of the vampire's next turn.

Actions
Corrupting Touch: Melee Spell Attack: +6 to hit, reach 5 ft., one target. Hit: 12 (3d6 + 2) necrotic damage.

Legendary Actions
The banshee 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. The lich regains spent legendary actions at the start of its turn.

Horrifying Visage: Each non-undead creature within 60 feet of the banshee that can see her must succeed on a DC 16 Wisdom saving throw or be frightened for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, with disadvantage if the banshee is within line of sight, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to the banshee's Horrifying Visage for the next 24 hours.

Wail (recharge on a 6): The banshee releases a mournful wail, provided that she isn't in sunlight. This wail has no effect on constructs and undead. All other creatures within 30 feet of her that can hear her must make a DC 16 Constitution saving throw. On a failure, a creature drops to 0 hit points. On a success, a creature takes 10 (3d6) psychic damage.

Drain Life: Ranged Spell Attack: +6 to hit, reach 60 ft., one creature. Hit: 14d6 necrotic damage on a fail, or half on a success. Also on a fail, its hit point maximum is reduced by the damage it took for 1 hour, but the spell can't reduce it below 1. Creatures immune to disease are unaffected by this spell, and effects that end disease relieve the reduced hit point maximum.

[miniatureaddict]

Good Banshee upgrade

[Deox]

So, instead of just straight up buffing the banshee, what about buffing the encounter?

Hazardous terrain, additional minions, environmental effects (lair actions), Legendary Actions, etc.

Example:
Wooded / Swampy are (difficult terrain), maybe bubbly tar muck?
Throw in Will O' Wisps (Their Consume Life ability is down right crazy after a Wail)
Lair Actions - That bubbly muck? Maybe it's boiling tar that does additional damage if PCs end their turn in it. Maybe it exudes noxious fumes? Maybe adds a darkness / fog effect?

[Mordna]

So, instead of just straight up buffing the banshee, what about buffing the encounter?

Hazardous terrain, additional minions, environmental effects (lair actions), Legendary Actions, etc.

Example:
Wooded / Swampy are (difficult terrain), maybe bubbly tar muck?
Throw in Will O' Wisps (Their Consume Life ability is down right crazy after a Wail)
Lair Actions - That bubbly muck? Maybe it's boiling tar that does additional damage if PCs end their turn in it. Maybe it exudes noxious fumes? Maybe adds a darkness / fog effect?

Thank you for your suggestion. I like the way you think. It's very useful for people who are struggling to stage encounters. However my request was to specifically buff the Banshee. :)

The stage is set, it is an encounter inside of a building that is an episode/map in a campaign.
Thanks though!

[DevilMcam]

My dm once ran one against our 4 lvl 12 PC.
A banshee with a bunch of shadows in complète darkness, this was scary as hell.
This was the end boss ofy character personnal story and it was awesome