As An Demon Slime You can transform Your physical form at will, assuming the appearance of any creature or object they have encountered or imagined. This grants advantage on Deception checks made to impersonate others or blend into their surroundings. Additionally,  You gain immunity to damage from non-magical sources while in their shapeless form.

You Have An Internal Storage That Can Store An Seemingly Unlimited Amount of Items (You Have No Weight) 
Analyze: On Wisdom, Intelelligence, Charisma, And Any Checks Involving these you are At an Advantage and Always Role With a +7

As An Demon Slime You  can assimilate the essence of Alive or defeated creatures, augmenting their own power indefinitely. After defeating a creature, You gain permanent bonuses equal to the creature's challenge rating: +2 to all ability scores, advantage on all saving throws, resistance to all damage types, and a 10% increase in maximum hit points.

To Assimilate an Alive Creature You Have to Roll A DC 18 Strength Check
Assimilating an Alive Creature Increeses The Amount of Essence Absorbed Granting you....
Permanent bonuses equal to the creature's challenge rating: +4 to all ability scores, advantage on all saving throws, resistance to all damage types, and a 20% increase in maximum hit points.

Demon Lord's Haki is an Extra Skill only obtainable by magical beings who have reached the level of a Demon Lord. It is also an Intrinsic Skill of Demon Slime. Allows the user's aura to exert a powerful spiritual pressure over their targets and inflict them with potentially lethal magical effects. It is possible for one to immediately perish if they are too weak, or cause one to lose their sanity.

Those Effected Must Role A DC 20 Saving Consituion Throw or Suffer one of the Chosen Effects.

Effects:
1. 22 (5d12 Psychic Damage)
2. Fear (Drop Any Held Weapons and Retreat)
3. Be Inflicted With Short Term Madness

Due to This Trait Being Created From Combining multiple other skills it has the effect of The Said Skills And More! 

Molecular Manipulation: It allows the user to manipulate the surrounding Magic Particles  to control the paths of molecules in the air to manipulate and utilize various elements. 
Magic Jamming: Ability to directly interfere with someone else's use of Magic in a much more controlled way (Roll A d100 and If you Roll 75 or higher you can change the effects of someones spell or cancel it) 
Perfect Magical Body: Spell Casting Speed Is Halfed






Magic Particles: Even mana is Physical! Its just on such a small scale its percived as abstract!

Universal Sense allows for the perception of nearly all things within a wide radius. It is an enhanced version of Magic Sense with superior sensory capabilities, allowing the user to perceive not only light and sound, but smell and heat in an extremely wide radius.

On your turn, you can use a bonus action to regain hit points equal to 2d100 + 9 (Once you use this feature 5 Times, you may not do so again until you complete a short or long rest.)

• Additionally, when you finish a long rest Regardless of levels of exhaustion you regain all expended hit dice, rather than half.

As An Demon Slime Your predatory instincts are unparalleled, allowing them to perceive and react to even the subtlest changes. They gain advantage on Perception checks to detect hidden creatures or objects, immunity to being surprised, and can take three reactions per round.

Demon Slimes possess an unparalleled resistance to infernal energies, granting them immunity to Elemental damage. Additionally, they have advantage on saving throws against spells and effects that attempt to manipulate or control their minds.

Demon Slimes exhibit an indomitable will and physical resilience. They have advantage on Constitution saving throws, and they are immune to exhaustion. Furthermore, they gain temporary hit points equal to their Constitution modifier (minimum of 1) at the start of each of their turns.

Demon Slimes possess an innate resistance to psychic damage and are immune to effects that would read their thoughts or detect their alignment. Additionally, they have advantage on saving throws against being charmed or frightened.

Demon Slimes possess the ability to manipulate and control demonic energy. Once per short rest, as an action, they can create powerful spectral tendrils of infernal energy that lash out at their enemies. This attack has a range of 60 feet and deals 6d6 force damage on a hit. The target must make a Strength saving throw (DC 8 + proficiency bonus + Constitution modifier) or be restrained and take ongoing damage equal to the Demon Slime's Constitution modifier (minimum 1) until the end of their next turn.

Demon Slimes have a deep connection to the abyssal planes, granting them the ability to cast the Darkness spell at will without requiring concentration. Additionally, they can see perfectly in magical darkness and have advantage on Charisma (Intimidation) checks made against creatures that can see in magical darkness.

When a Demon Slime is reduced to 0 hit points , they can tap into their infernal essence to ensure their survival. As a reaction, they immediately regain hit points equal to their hit point maximum and gain temporary hit points equal to twice their hit point maximum. These temporary hit points last for 1 hour. This ability can be used once per long rest.

Once per long rest, as a bonus action, Demon Slimes can unleash the full extent of their demonic power, undergoing a profound transformation. During this transformation, they tap into their infernal essence, enveloping themselves in an overwhelming aura of darkness and malevolent energy.

• Physical Ascendance: While in the transformed state, the Demon Slime's size increases to Large, and their gelatinous form takes on a terrifying visage. Their presence exudes an aura of fear, causing creatures of their choice within 30 feet to make a Wisdom saving throw (DC 8 + proficiency bonus + Constitution modifier) or become frightened for 1 minute.

• Demonic Fury: The Demon Slime's attacks become infused with demonic might. Their melee attacks deal an additional 3d6 necrotic damage, and any creature hit by their attacks must make a Constitution saving throw (DC 8 + proficiency bonus + Constitution modifier) or suffer disadvantage on their next saving throw.

• Infernal Resurgence: While in the transformed state, the Demon Slime gains resistance to all damage types and is immune to being charmed or frightened. Additionally, they have advantage on saving throws against spells and magical effects.

This transformation lasts for 10 minutes or until the Demon Slime chooses to end it as a bonus action. Once the transformation ends, the Demon Slime gains one level of exhaustion.