Alchemist's slime

Amorphous. The slime can move through a space as narrow as 1 inch wide without squeezing.
Chaotic Compsosition. The slime will regularly shift its contents, including the surface of its form. At the start of its turn, roll a d4. The ooze shifts to this form if it is not already there. It triggers any form shift abilities even if it is already there. The ooze also gains immunity to the damage type of its new form while in that form.

1-Fire. When the slime shifts to fire, each creature within 10 feet must make a Dex saving throw (DC 14) or take 7 (2d6) fire damage. Whenever a creature hits the ooze with a melee attack while within 5 feet of it, it takes 4 (1d6) fire damage.

2-Cold. When the slime shifts to cold, each creature within 20 feet must make a Con saving throw (DC 14) or be restrained until the start of the oozes next turn. If a creature starts its turn or moves within 10 feet of the ooze during its turn, its speed is reduced by 10 feet until the end of the turn, potentially preemptively ending movement.

3-Lightning. When the slime shifts to lightning, each creature within 10 feet must make a Dex saving throw (DC 14) or lose any prepared actions and be unable to take reactions until the start of the slimes next turn. A creature wearing metal has disadvantage on this saving throw. If a creature moves next to another creature during its turn while within 20 feet of the slime, both creatures take 2 (1d4) lightning damage from the static electricity.

4-Force. When the slime shifts to force, each creature 20 to 60 feet away from the slime must make a DC 14 Strength saving throw or be knocked prone. Ranged attack rolls against the slime or a target within 10 feet of the slime have disadvantage. If a ranged attack would miss a target granted disadvantage by this effect, the shot is deflected at a different random target within the attacks range. The slime makes this attack at +6 to hit, dealing the attacks normal damage.

Multiattack. The slime makes two attacks.

Pseudopod. Melee Weapon Attack: Non-force forms only. +6 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 3) bludgeoning damage plus 5 (1d8) damage based on its current type. 

Force slime. Ranged Weapon Attack: Force form only. +6 to hit, reach 100 ft., one target. Hit: 14 (3d8) force damage. 

Form pulse. (Recharge 6). The ooze shifts through every one of its forms, ending on one of its choice. It then makes an attack.

Reacitve form. When the slime takes damage of a type that does not match its form, it immediately shifts to that form.