Bebetzu

Erratic Movement (Tiny Only). When the bebetzu is tiny in size, it can move 10ft further as part of its move action and attacks against it are at a disadvantage.

Fur Coat (Tiny Only). When unmoving, the bebetzu may hide to become indistinguishable from a common dust bunny depending on the environment.

Siege Monsters (Huge to Gargantuan Only). When bebetzu is huge or larger in size, it receives the Siege Beast feature - Dealing double damage to any structures and buildings.

Shrink/Grow. As a bonus action, bebetzu grows or reduces its size one size category. The new size category has effects upon the bebetzu's attacks and some of its features.

Multiattack (Small to Tiny Only). When bebetzu is small or tiny in size, it receives the ability to strike as an multiattack. When attacking, the bebetzu hits twice with its icicle club attack.

Icicle Club Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: (2dX + 4 bludgeoning damage and 2d4 cold damage, where X is the size of the bebetzu. d4 for tiny, d6 for small, d8 for medium, d10 for large, d12 for huge, d20 for gargantuan.)

Icy Glare (Recharges at 6). The bebetzu chooses one target it can see within 30ft. of it. As an action, the bebetzu shoots an icy flare towards the target. The target must succeed on a DC 16 Constitution saving throw, or be paralyzed until the end of their next turn. While paralyzed this way, the target is vulnerable to bludgeoning damage and immune to cold damage as they are momentarily frozen solid.