Thwackey (5e Creature)
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Small plant, any alignment
Grassy Surge. A creature that hits the thwackey with a melee attack while within 5 feet of it must succeed on a DC 13 Strength saving throw or be restrained by a surge of plants for 1 minute. It can repeat the saving throw at the end of each of its turns, ending the effect on a success.
Outsize Strength. While grappling, the grookey is considered to be Medium. Also, wielding a heavy weapon doesn't impose disadvantage on its attack rolls.
Multiattack. The thwackey makes two branch attacks.
Branch. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage.
Grassy Glide (Recharge 5-6). The thwackey moves up to its speed in a straight line, including through other creature's space during this move, it ignores difficult terrain composed of plants. Each creature whose space it moves through must make a DC 14 Dexterity saving throw. A creature takes 12 (2d8 + 3) bludgeoning damage on a failed save, or half as much on a successful one. Whether it succeeds or fails, it is pushed to an unoccupied space within 5 ft. of the line. If no unoccupied space is within range, the creature instead falls prone in its space. The area the thwackey moves through becomes difficult terrain as grass begins to grow wildly.