[theory crafting] Option: Magical Theory

[8wGremlin]

I would like to discuss the ramifications of the following house-rule

At first level you decide where your character gets their magic from, you can go with what is written in the class, or you can take this option here.

Pick from Oath, Study, Innate

Oath: You have made some pact, sacrifice, or prayer to an extra-planar being. (a god, fae, devil, demon, far-realm thing), you offer prayers/mana/something to this being in return it offers you power, and a code of conduct that you must adhere to.

• Your casting stat is Wisdom, and all references to any other stat is superseded for magical class abilities/spells that you use. If you multiclass, the new class also uses this stat
• You have a set of 3 oaths that you must adhere to, please talk to your DM about these Oaths and your Patron.
• Failure to adhere to these oaths, diminishes your power (-1 casting stat mod for abilities) .

Study: You have learned your magical talent through diligent research and practice, you tend to write down your magical spells, notes and abilities in magical treaties and thesis, and practice daily. You may have made a pact with like-minded entities, but they do not hold the power over you. You can learn other spells from other Study theorists.

• Your casting stat is Intelligence, and all references to any other stat is superseded for magical class abilities/spells that you use. If you multiclass, the new class also uses this stat
• You must practice diligent everyday for at least 3 hours everyday, this can not be part of a long rest, but can be broken apart in to 3 x 1 hour short rests
• Failure to adhere to this practice diminishes your power (-1 casting stat mod for abilities).

Innate: magic flows through you, your blood sings with magic as you channel raw chaos and manipulate it to your whim. or perhaps you wield psionic powers of the mind, or your belief in your self is enough to wield such magic. But channeling this magic requires you to be in peek physical and mental health, being tired or drained physically can tax your ability to wield magic.

• Your casting stat is Charisma, and all references to any other stat is superseded for magical class abilities/spells that you use. If you multiclass, the new class also uses this stat
• You must keep yourself in peak physical condition, You must have Current HP
  
  • above 75% to cast fully,
  • above 50% to cast with penalty (-1 casting stat mod for abilities)
  • above 25% to cast with penalty (additional -1 casting stat mod for abilities)
  • below 25% to cast with penalty (additional -1 casting stat mod for abilities).

Questions:

1. How do you think this would affect game play?
2. Are there any issues that might arise from this?
3. Does this open up concepts that were previously closed to you?
4. Does this open up roleplaying aspects?
5. Does this rule interest you as a player?
6. Does this rule interest you as a DM?
7. Any other ideas/concepts that can improve this?

Note: please be aware any new system or concept will always be met with some initial resistance, as people don't like change.
This that doesn't mean that the change isn't good, or that the change isn't worthwhile. But we need to make sure that change is for the better and doesn't detract from the game. (Kaizen)

Thank you for your input.