Saturday Spell-Invisibility


Clumsy, invisible mage awakens a party of fighters while stealing a magical rod.

Invisibility magic in Mind Weave is a subject of some musing between myself and some of the testers.  When magic is based on raw elements and when encharges have such limited power (16 DoP) it is hard to put together an invisibility spell.  This doesn’t mean we haven’t come up with a number of ways to achieve the desired effect.  

Perhaps the simplest is to target the people who wish not to see you with mind magic that blocks you from their perception.  There are also powerful spells that can be cast over an area and veil people passing through it.  Simple darkness, while not as good for the stealth aspect of invisibility, can live up to the purpose of making oneself harder to hit, maybe while casting a spell.

However, today I am going to focus on the kind of invisiblity pictured: good, old-fashioned, Tolkien’s-One-Ring invisibility.  It takes more power than other approaches, and so won’t last as long, especially in a high light environment.  (I’m going to take a moment right now and warn, this spell by necessity gets down into the math of light physics in the game’s code.  It also ties in a couple important abilities and concepts from both the Tome of Light and Sound and the Tome of Order and Chaos.  If you don’t want to deal with that complexity, I’ll just say that this spell gives full invisibility in most indoor environments for nearly 4 minutes.)

For the sake of making it last a reasonable time, I’m going to assume a high-level, encharge-focused Magic-user with Spell Casting XI and Encharge Mastery III.  This means his encharges have a DoP limit of 20 rather than 16, he can discard 5 DoP, and all power in the spell is doubled using the bonus 20 DoP from Spell Casting.

To allow total you-see-through-me invisibility, the spell must expend dark energy in the form of anti-lumens equal to the total lumens of ambient light impacting the target and light energy equal in the form of lumens equal to the amount of light reflected from objects around him he is intercepting.  Assuming he is human sized, his body surface area (BSA) is 1.5-2 square meters, so in candle light or a full moon (1 lux) he only needs 2 lumens of each per turn (2 seconds).  In torch light he needs 10 lumens each turn to be safe.

With this information we can determine how many order fingers versus light and dark fingers we need to get the longest possible lasting invisibility.  Since the spell is “on” power and each DoP is doubled by Spell Casting XI, each order finger counts like 4, giving 16 charges in addition to the base 4.  Each light or dark finger  also counts as 4, giving 9600 lumens or anti-lumens each, reduced only slightly by the perpetual effect loss (less than 0.3% loss with just 2 order fingers).  Zo and Des arcs count for half of that.  Given our low light assumption, we will use only arcs for the light and dark, using half order, half chaos, full chaos, and full order fingers to maximize the number of turns and throwing out five superfluous light and dark DoP:

Left Hand:

Ku (Physical Radius): chaos

Des (Energy Arc): chaos(half)

Des (Energy Arc): chaos

Ku (Physical Radius): chaos(half)

Right Hand:

Ros (Stealth Radius): order

Zo (Negativity Arc): order(half)

Zo (Negativity Arc): order

Zo (Negativity Arc): order(half)

Zo (Negativity Arc): order

Zo (Negativity Arc): order (half)

Zo (Negativity Arc): order

Ros (Stealth Radius):

saying ‘on wu bi re liu’

This is a 25 DoP spell costing 280 sp.  With 11 DoP of Order, 6 DoP of Darkness, 3 DoP of Chaos duration, 3 DoP of Chaos energy, and 2 DoP of Light, we will throw out 3 DoP of Darkness and 2 DoP of Chaos energy (applying the final DoP of chaos energy, a half finger DoP, to light), since duration is our true limiting factor.  Each DoP of duration gives 8 turns over the minimum of 4, so with 14 DoP of duration we have 116 turns or 232 seconds (almost 4 minutes) of duration, with each DoP of light or dark giving 4800 lumens or anti-lumens, this is over 124 lumens of light that can be cancelled and emulated at any given time.

This is plenty for torchlight, or indeed for magical light, a room with windows, or braziers.  This spell is effective as long as light levels remain below 60 or so lux.  Outdoor daylight, even at sunrise or sunset, far exceeds this, so an invisibility spell in that kind of light would necessarily have a much shorter duration.  However, as long as the higher light configuration did not throw out any unwanted DoP, Extend Encharge could be used on it to continually and quickly renew it.

It should be noted that while I went to great effort to optimize this spell, a reread this morning found a way to reduce casting time by 5/dex seconds.  I’m sure there are further optimizations that can be done.  One of Mind Weave’s stated goals is to teach players to settle for what works without being sure it is absolutely the best possible.  This is one example of the best possible being hard to determine.

Any spells you would like to see implemented in the Mind Weave spell system?  A different kind of invisibility perhaps?  Suggest them below and we might get to them on a later Saturday.

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1 Response to Saturday Spell-Invisibility

  1. Pingback: Saturday Spell-Triggered Muffle | Mind Weave Role-Playing Platform

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