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

Ambusher. Matthew has advantage on attack rolls against any creature he has surprised.

Surprise Attack. If Matthew surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 10 (3d6) damage from the attack.

Multiattack. Matthew can make two melee attacks.

Slam. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage.

Read Thoughts. Matthew can magically read the surface thoughts of one creature within 60 feet of him. 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, Matthew can continue reading its thoughts, as long as Matthew's concentration isn't broken (as if concentrating on a spell). While reading the target's mind, Matthew has advantage on Wisdom (Insight) and Charisma (Deception, Intimidation, and Persuasion) checks against the target.