Bob the Blob

Tiny. Bob is roughly a handful.

Transparent. Even when Bob the Blob is in plain sight, it takes a successful DC 15 Wisdom (Perception) check to spot a blob that has neither moved nor attacked. A creature that tries to enter Bob's space while unaware of Bob is surprised by him.

Bouncy. Bob the Blob takes no damage from falling or from being thrown.

Shapeless. Bob can be molded into any shape and can squeeze through slits larger than 1 cm. He returns to cube shape after 10 minutes.

Blob. Bob feels no pain.

Flying Bob. A small or larger creature that has gained Bob's trust can pick him up and make a ranged attack to throw him at another creature. On a hit, Bob engulfs the targeted body part and the creature must make a DC 14 Constitution saving throw or take 4 ([roll]1d6[/roll]) acid damage. On a successful save the creature takes half the damage. The engulfed creature has disadvantage on attack rolls and takes 7 ([roll]2d6[/roll]) acid damage at the start of each of Bob's turns. If Bob engulfs the face of a creature, the engulfed creature becomes unable to breathe. An engulfed creature can try to escape by taking an action to make a DC 12 Strength check. On a success, the creature escapes and removes Bob from the engulfed area. If the creature does not immediately let go of or throw bob away, its hand is engulfed. If the creature attempting this has not achieved Bob's trust, they themselves become engulfed.

Multi-cube. When Bob the Blob takes slashing damage he can take a reaction to reduce the damage by [roll]2d10[/roll]. Bob is split in half, forming two conscious blobs. He can use a bonus action on his turn to merge all blobs occupying the same space together again.