You can change the basic makeup of your body. For example, you can move both arms to be on the same side, grow more mouths and eyes anywhere on your body, change in size by up too three feet, and create holes in your body. These alterations are extremely limited in detail so it is impossible to replicate the abilities of creatures like mimics, doppelgangers, or druids. If the DM considers something a major change, it will take a bonus action.

You can create a psuedopod that deals 1d4 bludgeoning damage and has a reach of 5 feet.

You can bite for 1d4 piercing damage with a reach of 5 feet. You can add 1d4 acid damage to this attack a number of time equal to your proficiency bonus each long rest.

You can speak, read, and write in common and undercommon.

Your movement speed is 30ft.

Your Constitution score increases by 1, and your Dexterity score increases by 2

The adhesive you secrete gives many advantages.

Your climbing speed equals your walking speed. You can climb upside down at half of your movement speed.

You have advantage when trying to keep a creature grappled or when grappling a creature.

You have advantage against any attempts to disarm you.

You can use your action to polymorph into an object, into you humanoid form, or back into your true, amorphous form. Your statistics are the same in each form. Any equipment you are wearing or carrying isn't transformed. You revert to your true form if you die. As long as you don't move, you are indistinguishable from an ordinary object. If someone interacts with you while you're shifted, you get an opportunity attack against them. The object can be no more than twice your weight and no less than one quarter you weight.