Mystrafume

The information below is for if a spellcaster contracts the Mystrafume parasite. Feel free to copy and modify these effects to fit your game.

Consequences for spellcasters:

• Every time the host takes a long rest, they must make a constitution saving throw with a DC of 10. This DC goes up by 1 each time they fail. For every failure, the parasite lays claim to a spell slot, starting with the lowest level spell slots until it reaches an even split as laid out below.

• The host will slowly over time lose access to their magic reserves, as the parasite figures out how much magic it can sustainably take, without removing its host’s magic entirely. The parasite will slowly get to the point where the host can only use half of the spell slots that they have for each level of spell rounded up. For example, a caster with 4 first levels, 3 second levels, and 2 third levels, would only be able to cast 2 first levels, 2 second levels, and 1 third level each day. If a caster has 1 spell slot for a level, they can’t cast that level at all.
• If a host would like to try and use a spell slot that the parasite has laid claim to, they need to make a constitution saving throw with a DC that is 10 + the level of the spell they are casting. If they fail, they take 1d10 psychic damage per spell level (for example a 3rd level spell would be 3d10), the spell fails, and they take a point of exhaustion. If they succeed, they cast the spell and the spell is extra effective at an amount of the DMs discretion.

Benefits for spellcasters:

• Magical absorption pool. Many of the effects below revolve around the parasite absorbing external magic. When it does you may add the amount specified, to your pool. This pool has a limit of 7 points. You may use the points in your pool to buy effects from the Mystrafume table. Your points reset to zero after a long rest.

• Magical resistance. Due to the parasites hunger for magic, any magic damage that the host would take is reduced by 1d4 + 1 for every 7th increment. For example a 24 damage spell would be reduced by 3d4 + 3. Add 1 point to your pool for each 7th increment.
• Magic for magic. Whenever you cast a spell that targets yourself, you may add points to your pool equal to the spell level. This does not work with ritual spells.
• Always hungry. Anytime a damaging or healing spell of 1st level or higher is cast within 30 feet of you (this includes your own spells), that amount of healing or damage is reduced (to a minimum of 1) by your proficiency bonus and you may add half of your proficiency bonus rounded down to your pool.

Absorption Pool Table:

You may spend points on the abilities below as you use them.