Serpent and Void
Before the fall of Atlantis 300 years ago Thule was land of magic. Each of the elder races such as the Dwarves, Elves, or Halflings were masters of arcane & divine magic and part of the pure magic weave that permeated Thule.
The Atlanteans learnt magic from the elder races but they were not part of the weave. Instead they drew on the magic as one might draw water from a well, manipulating the captured power to create or destroy.
While the reason for the cataclysm that destroyed Atlantis is unknown, the result was magic across Thule was disrupted and the magical weave forever tainted. Masters of arcane and divine magic are now rare and those few who dabble must learn to control a tainted magic weave.
Magic in Thule is a dark and dangerous force that can destroy a spell caster.
All wielders of Magic are referred to as Sorcerer’s in Primeval Thule. Non users view all who practice magic with suspicion, even when it benefits them. A caster may gain advantage on Intimidation or Persuasion checks after displaying magical power at the GM’s discretion.
What is a Spell?
The Players Handbook page 201 defines what a spell is. For the purposes of the following rules Cantrips are not spells.
House Rule: Sacrifice for Power
A spell caster may sacrifice a helpless and unwounded living being for spell slots.
The sacrifice takes a full round per victim and requires a method of doing so which does not use magic.
Each victim sacrificed provides 1 bonus spell slot per full CR or CR x2 for non magic induced true self-sacrifice.
The bonus spell slots can be molded to duplicate any combination spells slots the caster knows. For example the a fifth level wizard has four 1st level spell slots, three 2nd level spell slots, and two 3rd level spell slots. After sacrificing a CR 4 living being the wizard now has four bonus spell slot points and could cast four 1st level spells or one third and one 1st level spell.
The bonus spell slots are available for use until the next Long Rest is taken.
The maximum bonus spell slots that can be stored safely are equal to your spell casting ability score.
Stored spell slots require concentration to control (see PHB p203), a failure to maintain control or overloading spell slots points results in the release of all spell slots (including normal) with dire consequences.
House Rule: Taint
All wielders of magic expose themselves to the tainted magic weave.
Every time they cast a spell (see what is a spell above) the caster must make a Spell Check by rolling D20 + proficiency bonus + spell casting ability score bonus – the casters current level of taint.
On a natural 1 or a modified 1 or less, the caster gains 1 point of taint.
Taint can be removed by using spells that affect Disease. The recipient of such a spell can make a Constitution save DC 10 + the current level of taint.
Success removes 1 point of taint.
Characters can acquire taint by exposure to locations, items and creatures affected by tainted magic weave.
It is rumored that remnants of the pure magic weave still exist and that contact with it can remove or help resist taint.
Taint affects characters in dark and dangerous ways.