Avena

Change Appearance. Avena can use her action to polymorph into a Medium humanoid she has seen, or back into her true form. her statistics, other than its size, are the same in each form. Any equipment she is wearing or carrying isn’t transformed. she reverts to her true form if she dies.

Poisonous Vengeance (Mythic Trait; Recharges after a Short or Long Rest). If Avena is reduced to 0 hit points and is in her lair, she doesn’t die or fall unconscious. Instead, she regains 50 hit points. In addition, She glows bright purple.

Multiattack. Avena makes 4 attacks with her daggers or 2 attacks with her rapier.

Dagger. Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 5 (1d4 + 3) piercing damage.

Rapier. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage.

Unsettling Visage (Recharges after a Short or Long Rest). Each creature within 30 feet of the changeling must succeed on a DC 13 Wisdom saving throw or be frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Steel Dragon's Claw. Avena can use an action to produce one of the following poisons from her hand:

- Poison, Basic. You can use the poison to coat one slashing or piercing weapon or up to three pieces of ammunition. Applying the poison takes a bonus action. A creature hit by the poisoned weapon or ammunition must make a DC 10 Constitution saving throw or take 1d4 poison damage. Once applied, the poison retains potency for 1 minute before drying.

- Malice. A creature subjected to this poison must succeed on a DC 15 Constitution saving throw or become poisoned for 1 hour. The poisoned creature is blinded. These poisons are powders or gases that take effect when inhaled. Blowing the powder or releasing the gas subjects creatures in a 5-foot cube to its effect. The resulting cloud dissipates immediately afterward. Holding one's breath is ineffective against inhaled poisons, as they affect nasal membranes, tear ducts, and other parts of the body.

- Burnt Othur Fumes.  A creature subjected to this poison must succeed on a DC 13 Constitution saving throw or take 10 (3d6) poison damage, and must repeat the saving throw at the start of each of its turns. On each successive failed save, the character takes 3 (1d6) poison damage. After three successful saves, the poison ends. These poisons are powders or gases that take effect when inhaled. Blowing the powder or releasing the gas subjects creatures in a 5-foot cube to its effect. The resulting cloud dissipates immediately afterward. Holding one's breath is ineffective against inhaled poisons, as they affect nasal membranes, tear ducts, and other parts of the body.

- Midnight Tears. A creature that ingests this poison suffers no effect until the stroke of midnight. If the poison has not been neutralized before then, the creature must succeed on a DC 17 Constitution saving throw, taking 31 (9d6) poison damage on a failed save, or half as much damage on a successful one. A creature must swallow an entire dose of ingested poison to suffer its effects. The dose can be delivered in food or a liquid. You may decide that a partial dose has a reduced effect, such as allowing advantage on the saving throw or dealing only half damage on a failed save.

- Truth Serum. A creature subjected to this poison must succeed on a DC 11 Constitution saving throw or become poisoned for 1 hour. The poisoned creature can't knowingly speak a lie, as if under the effect of a zone of truth spell. A creature must swallow an entire dose of ingested poison to suffer its effects. The dose can be delivered in food or a liquid. You may decide that a partial dose has a reduced effect, such as allowing advantage on the saving throw or dealing only half damage on a failed save.

Poison Weapon. Avena can apply poisons to her weapons as a bonus action.

Avena can take 2 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. Avena regains spent legendary actions at the start of her turn.

Stab. Avena makes two attacks with her daggers or one with her rapier.

Poison Claw. Avena uses the "Steel Dragon's Claw" action.

If Avena's mythic trait is active, she can use the options below as legendary actions, until she is reduced to 0 hit points or takes a short or long rest. 

Twin Stab. Avena makes Four attacks with her dagger or two attacks with her rapier.

Deadly Poison (Costs 2 Actions, can only use once per battle). Avena sprays a deadly poison gas out from her right hand. Each creature within 15 feet of Avena must make on a DC15 constitution saving throw taking 30 (12d8) poison damage on a failed save or half on a success.