Boon of Bhaal

 Your assistance towards a favorite servant of the Dread Lord Bhaal grants you this effect:

 You become branded with the symbol of Bhaal, a Skull surrounded by a ring of bloody droplets and furthermore are able to tap into the powers of the Bleak Eternity of Gehenna. 

Using these powers grants you one use of a special action -- called legendary action -- outside your turn. Only one legendary action option can be used at a time and only at the end of another creature's turn. You can regain the spent legendary action at the start of your turn if you roll a 5 or 6 on a 1d6 roll. You can forgo using it, and you can't use it while incapacitated or otherwise unable to take actions. If surprised, you can't use it until after its first turn in the combat. After using one of the possible legendary actions, the same one can't be used again until a long rest has been had.

The choices for the legendary action are as follows:

1. Blend into Terrain. You takes the Hide action and move up to half of your speed.
2. Blood in the Eyes. You make a melee weapon attack, on a successful hit, the creature takes the normal damage from the attack and must succeed on a DC (16) Constitution saving throw. On a failed save, the creature is blinded as blood pours into its eyes for 1 minute. A blinded creature can repeat the saving throw at the end of each of its turns, ending the effect on a success.
3. Chosens' Bloodburst. You can tap into Bhaals powers to shoot a condensed high-velocity stream of Blood from your hands. Roll a ranged spell attack, on a hit the target takes 3d6 force and 2d6 poison damage. 
4. Channel Negative Energy. You seep with foul, bloody necrotic energy, channeling the negative energy of Gehenna. Each creature of your choosing within 20 feet of you takes 4 (1d8) necrotic damage and only regains half its normal hit points from magical healing until the end of its next turn.
5. Channel Positive Energy. You start to burn with brilliant radiant energy, channeling the positive energy plane. Each creature of your choosing within 20 feet of you regains 5 (1d10) hit points and has advantage against all saving throws that deal necrotic damage for 1 minute.
6. Frightening Curse. You target a creature within 30 feet of it that you can see and force them to make a DC (13) Charisma saving throw. On a failed save, the target is cursed for 1 minute. While it is cursed, it has disadvantage on saving throws against being frightened and all of your allies have advantage on the first attack each round against the creature.
7. Switch Spells. You can choose unused Spell slots you have, up to a combined level of 7 and spend them to regain a Spell slot of the combined level.