Changeling Assassin

Assassinate. The changeling has advantage on attack against creatures that haven't taken a turn yet. Hits against surprised creatures are critical.

Psionic (25). The changeling has 25 psi points that are used for many of its psychic abilities. All psi points reset daily at dawn.

Adaptive Body. The changeling doesn't need to eat, sleep, or breathe, and ignores the effects of extreme heat or cold (but not cold or fire damage).

Shapechanger. The changeling can use its action to polymorph into a Small or Medium humanoid it has seen, or back into its true form. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Read Thoughts. The changeling can magically read the surface thoughts of one creature within 120 feet of it. The effect can penetrate barriers, but 3 feet of wood or dirt, 2 feet of stone, 2 inches of metal, or a thin sheet of lead blocks it. While the target is in range, the changeling can continue reading its thoughts, as long as the changeling's concentration isn't broken (as if concentrating on a spell). While reading the target's mind, the changeling has advantage on Charisma (Deception, Intimidation, and Persuasion) checks against the target, and automatically succeeds on Wisdom (Insight) checks against the target.

Amulet of Proof Against Detection and Location. The changeling is hidden from divination magic. It can't be targeted by such magic or perceived through magical scrying sensors.

Dagger of Warning. The changeling has advantage on initiative and can't be surprised.

Multiattack. The changeling makes two melee attacks, each of which it can replace with one use of Mind Thrust or Shadow Beasts.

Ethereal Dagger (1-4psi). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (1d4+2d6+4) psychic damage +6 (1d10) psychic damage per psi point spent.

Mind Thrust. The changeling targets one creature it can see within 120 feet of it. The target must succeed on an Intelligence saving throw or take 1d10 psychic damage.

Shadow Beasts (3 psi; concentration, 1 min.). The changeling can cause two shadows to appear in unoccupied spaces it can see within 60 feet of it. The shadows last until its concentration ends, and they obey its commands telepathically. In combat, roll for their initiative, and choose their behavior during their turns. When this effect ends, the shadows disappear.

Adaptive Shield (3 psi). When the changeling take acid, cold, fire, lightning, or thunder damage, it can use its reaction to gain resistance to damage of that type (including the triggering damage) until the end of its next turn.

Ring of Evasion (3 times per day). When failing a Dexterity saving throw, the changeling can use its reaction to succeed on that saving throw instead.

The changeling 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 changeling regains spent legendary actions at the start of its turn.

Darkness (1–4psi). The changeling creates an area of magical darkness, which foils darkvision. Choose a spot you can see within 60 feet of you. Magical darkness radiates from that point in a sphere with a 10-foot radius per psi point spent on this ability. The light produced by spells of 2nd level or less is suppressed in this area.

Ethereal Dash (1-4psi). The changeling increases its walking speed by 10 feet per psi point spent until the end of its action then moves up to its walking speed. During this action it is considered invisible and doesn't provoke attack of opportunity.

Agile Defense (2 psi). The changeling takes the Dodge action.