Homebrew Sentient Slime Species Details

Magic-fueled beings

Slimes have a core, a source of magic that controls their amorphous bodies. Without magic in reserve, the core can’t sustain the body and needs to recover. Because of their magical nature, slimes are proficient with magic, as well as heavily influenced by it. Slimes can live in almost any environment and learn to blend in, which lets them both change their colour and elemental affinity over time. Fueled by magic means as long as the core is safe a slime can live forever and always recover to its original form or adapt to a new environment. Sentient slimes take longer to change their elemental affinity, but being exposed to enough of it without dying will change their alignment. Consuming other slimes’ cores will immediately change their alignment to the one they just consumed for a short time. Due to practically being monsters, they don’t see survival of the fittest by consuming other slimes as wrong. Since slimes don’t have eyes, their eyesight is mainly composed of darkvision unless some item helps them see as other races do.

Liquid bodies

Slime bodies are composed of an almost liquid, jellyish substance. It allows them to survive a lot of hazards by sacrificing some of the material and moving their only ‘real’ body, their core, around. The same substance can be used to heal the core as long as it’s not too broken. The liquid mass is lost when exposed to dangers and recovered with food. They are resistant to any physical damage because of their soft bodies. The same way dungeon traps and long falls won’t do much to injure their core, and moving it around isn’t difficult when needed. Instead of sleeping, slimes just become idle to recharge before continuing. 

New to society

It is still unknown how slimes gain sentience, but it started fairly recently. There are very few slimes in mundane society and when seen, they are sometimes treated more like the monsters they are. The majority of sentient slimes know nothing of society or are still learning, so they are sometimes gullible and mostly don’t know how to read their room or how to behave. They are very curious, but stay aside from dangers by instinct. Those slimes who integrate into society tend to be neutral or friendly, unused to holding grudges and quite blunt. If there are any slimes who take to adventuring, it’s either curiosity or them slowly discovering themselves and what they like. Jokes or expressions may be beyond them, and not everyone has a good grasp on languages. Slimes don’t have a language, so they gradually learn from the ones they’re exposed to.

Sentient Slime Traits

Your sentient slime character has a variety of natural abilities, developed before gaining sentience for survival.

Slimeshifting

 You know a cantrip named slimeshift, which lets you alter your body indefinitely. Since your body isn't solid, it can change shape according to necessity. Running liquids will automatically dispel the spell for the areas where it comes into contact with you.

Blindvision

Without vision you can't see, so you have to use the vibrations as your sight. You have 120 ft of tremorsight.

Naturally stealthy

Being small by nature and capable of changing shape, hiding behind the silhouette of a creature larger won't be difficult for a slime. You can attempt to hide even when you are obscured only by a creature that is at least one size larger than you.

Toughness

As a survival mechanism, slimes slowly become denser. Your hit point maximum increases by 1, and it increases by 1 every time you gain a level.

Elemental Affinity

Depending on the colour of the slime, they come from different environments and know the strengths of one element, gaining 1d6 bonus damage with all sources of said element at level 1, increasing to 2d6 at level 6, 3d6 at level 11 and 4d6 at level 16. Surviving in one environment meant they weren't exposed enough to other environments and have weaknesses to those elements.

Colour	Elemental damage	Vulnerabilities
Red	Fire	Poison, Cold
Blue	Cold	Acid, Thunder
Yellow	Thunder	Lightning, Fire
Green	Acid	Thunder, Lightning
Purple	Poison	Cold, Acid
Orange	Lightning	Fire, Poison

Amorphous

You core is a crystal-like orb 1.5 inches in diameter, and it holds your liquid body together. As long as it can fit through a gap, so can the rest of your body.

Magic reserve

When you cast spells, some of your core’s magic reserve is used, and if too much is spent your body falls apart and the core is exposed. Your magic reserve limits you to 2 spells before fainting at level 1, increasing by 1 every 2 levels. The use of magic on cantrips is negligible. You unconditionally recover magic at a rate of one spell’s worth every 30 seconds and recover your whole reserve after a short rest.

Slime core

You have a core that holds your body together with magic. You can use your core or the cores of other slimes as an arcane focus. Consuming a slime core changes element to theirs for 1 hour. If you're unconscious or reach 0 hp, your body melts into a puddle of slime and your core is left among it. It has no vulnerabilities or resistances, and needs to be hit again at 0 hp to be killed off. Instead of sleeping the slime becomes completely idle for 4 hours to recharge. You can climb terrain at a speed of 20 ft and swim at a speed of 40 ft, but you lose all shape when you swim. The liquid body is resistant to piercing, slicing and bludgeoning damage. You are immune to fall damage, but take time to recover your mass when you land.