Entities - Third Pass

The Barony setting document I put up a couple of days ago is built around a set of 11 classes, and two of them, the Academic and the Artist, significantly make use of a new magic system based around language and magical beings called entities. I wanted to make some actual rules for using these, to reduce the work for the DM in running a game with these classes.  

This is probably not how I would use them; in my own game I prefer things like magic and magical contracts to be less clearly systematised; but I think it's important to give the option for games with an expectation of a properly systematic DnD-style magic system.

• Entities are statted NPCs without any physical stats. 
• All entities are incorporeal (this is a slight retcon for simplification around possession rules). 
• Entities can be as intelligent as: a dog, a crow, a human child, an adult human, a very smart human adult.
• Entities who have at least human level intelligence will speak their own pattern language.
• Entities know magic, and cast with MD like a GLOG wizard. Entities of low intelligence probably know a single spell, entities of high intelligence know spells like a normal GLOG wizard. The player will only have access to these spells through favours, so more spells does not mean more casts - it usually means greater flexibility. 
• Entities can possess human bodies. The human can be willing (many class features revolve around this), or it can be done on an unwilling target. On an unwilling target, make an opposed Char check. The unwilling human may then save twice more on subsequent turns, and if all three tests are failed then the entity is in control until it decides to leave (or until the host is force-fed stimulants).
• Humans possessed by entities can cast the entity's magic, and take a level of exhaustion and 1 point of damage every time the entity possessing them rolls a 4-6 on its MD. If the host's inventory is maxed out with exhaustion, the damage goes up to d3. An entity can also choose to roll a 6 on their MD at the cost of d6 damage to the host. Human bodies are not meant to perform magic. There are many entities that will callously kill humans this way. 
• Humans possessed by entities also do not feel pain, or fear of anything that will only harm the human body. 

Casting magic with your entity!

• Entities can enter into a relationship with you if you speak their language. To communicate at all you must at minimum speak the same metalanguage. If an entity speaks their own pattern language (not a metalanguage), taking the time to learn that language will mean that they like you as a default.
• Entities can be called using their names. Entities who like you will come when you call. Make a Char check with an appropriate penalty (based on how powerful and prideful the thing you're trying to summon is) if you try to summon something without a preexisting relationship. Entities can also be trapped in various ways - they cannot answer a summons if trapped. 
• An entity who likes you will do you one favour a day for free, as long as the relationship does not sour. Entities do not distinguish between magic and mundane favours. 
• You can try to convince an entity to stick around and provide you more favours. This will always require payment of some kind. Entities like different things, and will take all of the classical mystical currencies (years of life, firstborns, etc.) in addition to blood, sugar, iron, gold, memories, youth, health, beauty.

Notes on artist entities!

• Artists are in permanent contact with their entity, and are assumed to have its unconditional love and support. They also get full access to their entity's magic permanently when they get their B template. 
• This means that at a certain point artists will be casting with MD like a normal GLOG magic user. 
• In my own games I probably would not give artist entities access to direct damage spells. In my mind they would have perception and sensitivity based magic, things like true seeing, protection from Law and Chaos, charm, illusion, etc. etc. 
• I would also limit the power of artist entities relative to the ones in the wild that Academics speak to and bargain with. You could make this a result of the relative youth of artist entities, who only came into the world when their artist did. 
• They would also probably have the ability to forge/create artefacts of various kinds (I could see a summonable Blade of Intention with a blade cut away from the fabric of the world, a sort of painter-hexblade). 
• YMMV, maybe you want your warlock artists casting fireballs. 

That seems functional enough? Any and all feedback gratefully received. 

The Apparition, by the very great Gustave Moreau.