GURPS 4e Magic: Area vs SM+1 +

[Eric Funk]

Hello GURPS Masters

I am coming back to GM a campaign and with three spellcasters in the party they are just starting to get into larger area Resistable spells. As the subject hints I am wondering about how large Size Modifiers affects Area/Regular-Resist spells.

1) I can understand single-target Regular spells require increased costs* but for larger creatures (say even a horse **), if Mass Sleep is cast, are they

A) unaffected by default castings of Area spells?
B) affected if within the area, assuming larger SM creatures take up more hexes and thus are in effect consuming more spell energy, effectively fulfilling B239* ?


2) In either case my reading for Resistable spells they are unaffected if partly in the area. (B239, M11 say Area spells "affect everyone in the area of effect"... possibly read either way for partly in the area of effect, but they are not wholely so are not really IN...?) Recall for normal SM+0 humans a prone person occupies two hexes... (p.B385)


* B239, M11
** SM+1 3 hexes p.B459

Thoughts?

Thanks!

-
"Knowledge Brings Fear" -- Motto of Mars University, Futurama

[hal]

Hi Eric,
Because Area spells are effectively the same as Regular spells, but for their area of effect and the fact that you can target an area for spell casting instead of one specific target - this is how I understand the rules to mean...

Base cost is determined by the spell itself. If you have a larger sized "target" for the spell, you multiply the base cost of the spell in order to affect a given target. So, to cast a single spell of SLEEP for example, you have to multiply the base cost by SM modifiers. The same would hold true for area spells. First, determine the base cost for the spell as given (which is for SM + 0 targets) then multiply it by the SM+1 value (ie double the cost), then use that as the base cost for a 1 hex radius spell (ie one hex of effect). Since Minimum radius for Mass sleep is 2 hex radius, you pay the cost of x2 for affecting SM+1 targets, and then another x2 for a minimum 2 hex radius effect.

Note: if you cast a spell with a cost for a SM+0 target, it will not affect a target that is SM+1 or higher just because the spell lacks the "Oomph" required to affect the larger target.

Thus, if you want to cast the spell against a herd of horses within a 10 hex radius spell, you would have to do this:

Mass Sleep cost 3 x 2 (SM+1 targets) x 10 or 60 fatigue. Any and all creatures sized SM+1 and under, now have to resist the spell if they are within that area of effect. Even if only HALF of the creature's body is in the area of effect, they suffer the effects of the spell itself.

Per other rulings regarding spell casting and being able to control who/what the area spell WILL affect that the time of casting, you could in theory, cast the Mass Sleep for horses, and ignore all else inside the area. You could affect all horses and men, but not tigers (assuming one was within the area of effect). You could have it affect everything within a full circle save for a small wedge effect.

60 energy to cast a spell on that many hexes is a lot, but then again, the number of actual hexes contained within that area is rather sizable. A 2 hex radius spell affects 7 hexes or has a diameter in reality - of 3 hexes. So a 10 hex radius has a diamter is by measurement of (10-1)*2+1 yards or 19 yards in diameter.

Hope that helps.

Hal

[Dalin]

I’ve always just allowed area spells to work if the target was entirely contained within the area, keeping in mind the fact that area spells are usually four yards high. Something taller than four yards would require twice (or more) the area of its footprint to stack enough areas on to contain it. If a giant, however, curled up in a fetal position on the floor, it could be affected by a smaller area.