Riffing on: GURPS Threshold Limited Magic

The metaphysics are simple, really. Each of us is born with an immortal soul, a tiny fraction of The Infinite, inside of us. And that soul retains an affinity for, and connection to, the Astral Plane. All of the mana in our world comes to us from the Astral Plane, by way of these connections. Over time, mana builds up in our bodies, permeating us. When one is said to have been "lucky", this is really just a manifestation of The Infinite taking care with us, to see us safely through life's tribulations. Those that learn the necessary rituals can instead harness this energy to their own ends, using it to power true Magick.

This is a variant take on Threshold Limited Magic, from Thaumatology. I've long thought that TLM is one of the more evocative ideas presented in the book (if a bit heavy-handed on the default consequences chart presented). This version is more flexible, and I think fairly flavorful, while providing some real teeth to keep casters from abusing their power.

Instead of a single overall Threshold, the system uses three distinct break points along the way. The first, and most generally useful, is the mana that builds up over time inside the mage's body, accumulating from the Astral Plane. This gives every mage an initial Threshold of 5 + Magery that he can pull from at any time. These points are refreshed at an accelerated rate as well, with one point of tally dropping every 15 minutes.

If a mage's tally exceeds this first threshold, he begins to dip into the mana that is stored in his very soul. The threshold for this second tally is capped at 12 for all casters, regardless of their powerThis is at least temporarily damaging to the self, and has immediate consequences. For every three points (or fraction thereof) that the tally exceeds the initial threshold, all Will rolls including self-control rolls, is penalized by 1 - representing a weakening of the soul of the caster. This tally, kept separately from the first, recovers at a slower rate, recovering just two points each day, one point each at noon and midnight. Note that this is entirely separate from the first tally, and can be recovered at the same time without interference.

Finally, if the caster's tally exceeds even this threshold, he has a third threshold of 10 more points that represents pulling mana directly from the Astral Plane. This process is daunting, but for those first ten points does not incur any rolls on the consequence table. The in-game impact of this is that a rift is made between the two planes, a wound on the wall between realities. For every two points this tally rises, the more obvious this becomes to those with the power to see it and any attempt to search for the caster on the Astral Plane, or any attempt to use magic to locate the caster, gains a +1 bonus. Also, range penalties for spells cast against this individual are reduced by the same margin.

When the desperate caster exceeds even this threshold, he has opened a significant gap between worlds, and invites all manner of difficulties upon himself. This is the point at which rolls begin to be made on a specialized table of calamities, suited to the campaign world.

Reductions in this third tally, including values that exceed it, recover even more slowly and under stricter circumstances. For the tally to drop by a single point, the caster must refrain from all magical activity of any kind for a full day. If he or she does so, from one sunrise to the next, the tally will drop by a single point. Until the tally for this third tier has dropped sufficiently, the caster retains the associated penalties.

One of the effects of this lore on game mechanics - Luck (at any level) is mutually exclusive with Magery (at any level) - you can be lucky, and rely on your internal store of mana to see you through tough times, or you can tap that power for your own ends, but not both.

Some sample Consequences (roll 3d + 1 for every 5 points of tally over the third threshold):

3: A benign force from the other side aids your cause. Regardless of the energy cost required to cast the spell, your third tier tally is reduced to 10.
4-8: No immediate effect. You've managed to avoid immediate notice.
9-10: You feel something that isn't there brush up against you and seem to pass through you. The echo of distant laughter rings in your ears.
11-12: Psychic backlash leaves you drained and with a thunderous headache. This costs you 1d Fatigue points.
13-14: Caster has a vision of his own death. Make a Will roll at -4 or stand frozen for 1d seconds.
15: as 9-10, but you are also Stunned (B.420).
16: a malevolent spirit bursts through from the Astral and attaches itself to the caster's soul. Gain one psychological disadvantage at the GMs discretion (not to exceed 5 points in value). It will automatically flee when all three of the caster's tallies are reduced to 0.
17: caster bleeds from the ears and nose. Take 1d-3 (min 1) HP of damage and act at -1 DX and IQ on all actions for 1d minutes due to ringing ears and dizziness.
18: a stronger spirit attempts to use the rift to possess the caster. Handle this as the Possession spell, cast at a level of 15 + 1 for every 5 points of tally over the third threshold. The spirit will attempt to possess the caster 1d times before giving up. If the possession succeeds, the caster may make additional attempts to reassert control each day, at a cumulative -1 each day until his effective Will roll drops below 3, at which point he may not attempt further rolls. The possession can be ended by another caster with an appropriate spell to end the Possession spell.

Now, with the understanding that this is utterly untested in play, what do you think, sirs?


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