Angel of Death

Doomed to Die. When a creature that can see Thanariel starts its turn within 120 feet of Thanariel, Thanariel can force it to attempt a DC 30 Constitution saving throw. On a failed save, if the creature has 100 or fewer hit points, it dies permanently. If it has 101 or more hit points, it is instead reduced to 100 hit points. For each successful save, the DC is increased by 3. For each failed save, the DC is reduced by 5. Creatures who see Thanariel cannot regain hitpoints until the start of its next turn.

Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it cannot see Thanariel until the start of its next turn and is cursed until it sees Thanariel next. While cursed in this manner, a creature takes double damage on critical hits, loses all resistance and immunity to damage, cannot regain hit points, and dies permanently if it is reduced to 1 hit point. 

Mythic Resistance (3/Day). When Thanariel fails a saving throw, it can choose to succeed instead. Alternatively, it can spend one of its unspent legendary actions to succeed instead. If Thanariel succeeds twice on the same feature, it is immune to that feature until the start of his next turn.

Packman. Thanariel always goes first in initiative. If he is reduced to 0 hitpoints, he pops back at the center of the map, more powerful.

Reaper’s Mercy (2/Round). Thanariel can choose to deal an extra 140 (40d6) necrotic damage when it hits a living target with a weapon attack. Additionally, Thanariel’s weapon attacks are magical, score a critical hit on rolls 18-20, ignore immunity to critical hits, and Thanariel cannot be disarmed of its scythe.

Shadow of Death. If creatures do not see Thanariel, he is hidden.

Scythe. Melee Weapon Attack: +24 to hit, 15 ft., all targets. Hit: 41 (4d12 + 15) slashing damage. Creatures hit by Thanariel's scythe have their movement speed set at 30 feet until the end of their next turn.

Inevitable Stride. Thanariel becomes an incorporeal shadow until the start of its next turn. While in this state, Thanariel can pass through other creatures, objects, and magical barriers as though they were difficult terrain. If Thanariel ends this movement inside an object, it is shunted to the nearest unoccupied space and takes 5 (1d10) force damage for every 5 feet it is moved in this manner.

The Culling (Recharge 5–6). Each creature of Thanariel’s choice that it can see within 300 feet of it must succeed on a DC 30 Wisdom saving throw or be subjected to its Doomed to Die feature (in initiative order), even if it would ordinarily be unaffected or outside the effect’s range.

Opportunity Attack (1/Turn). Thanariel takes an opportunity attack when a creature enters or exits his reach, even if it takes the disengage action.

Thanariel can take 3 legendary actions, moving up to half his movement speed and 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. Thanariel regains spent legendary actions at the start of its turn.

Move. Thanariel moves up to his movement speed.

Hide. Thanariel takes the Hide action.

Scythe (Costs 2 Actions). Thanariel makes a single Scythe attack.

Touch of Unmaking (Costs 3 Actions). Thanariel touches an object or magical effect within reach. If the target is an object or structure, it is immediately destroyed. If the target is a magical effect, the effect immediately ends.