Multiattack

The scarecrow uses Scare and makes two slam attacks.

Slam

Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) bludgeoning damage.

Scare

Each creature of the scarecrows choice within 30 feet that can see the scarecrow makes a DC 12 Wisdom saving throw. On a failure it is magically frightened for 1 minute. It repeats the saving throw at the end of each of its turns ending the effect on itself on a success. If a creatures saving throw is successful or the effect ends for it it is immune to Scare for 24 hours.

Hat of Illusion (1/Day)

While wearing a hat or other head covering the scarecrow takes on the illusory appearance of the last living humanoid to wear that hat. It requires a DC 12 Insight or Perception check to recognize the illusion. The illusion ends when the scarecrow is touched takes damage attacks or uses Scare or when the scarecrow chooses to end it as a bonus action.