Catterball

Rubbery Flesh. Immune to any form-altering spell/effect and has advantage on ability checks and saves to escape grapple. Can move through a space as narrow as 1ft. wide with o squeezing.

Standing Leap (Ball Form Only). Its long jump is up to 60' and its high jump is up to 30 feet with or with o a running start.

Slam (Extended or True Form Only). Melee Weapon Attack: +5 to hit, 5 ft., one target, 6 (1d6+3) bludgeoning damage.

Snap Back (Extended Form Only). Violently returns to its true form. Each creature within 5 ft. of it: 4 (1d8) thunder or 9 (2d8) if catterball has extended its reach to 15 feet and is deafened for 1 min (DC 12 Dex half damage not deafened). A deafened creature can make a DC 12 Con save at the end of each of its turns success ends effect on itself.

Change Form. Can extend its body roll up into a ball or return to true form. Each time it extends its body its reach with slam increases by 5 feet max 15 feet and Armor Class decreases by 1.