Magic Defenses using GURPS MAGIC

[hal]

Hello All,
Having recently seen a thread on "GM defenses against invisibility and other spells" I thought to myself "Now would be an interesting to broach magical defenses for castles".

So, here is the premise. A real World Castle/Keep - that can be referenced by any means available to an enterprising individual, including by means of a SJGames product by Dan Howard...

Restormel castle.

All mages must be built using 150 point characters. NO Magery 3 mages allowed. All energy using ritual spell castings and extra energy from spectators will be quantified using "reaction rolls". Neutral reactions grant zero energy, Good+ reactions generate energy, and bad- reactions result in negative energy subtracted. Spell backfires affect EVERYONE in the ritual spell casting (this is why reaction rolls are used for the number of participants).

The idea here is to find the best defenses against magic that is possible given the limited resources. Later, we'll look at other ways of improving the castle defenses by contractors hired from other locations (including Magery 3 mages).

Anyone up for this discussion?


Possible changes to the original premise:

Builder of the castle hires specialist mages from nearby Cities, or perhap

[Taneli]

So, how many mages do we get to play with?

Assuming something like IQ 15 [100], Magery 2 [25], and 25 points in spells [25], [-75] points in negative traits and quirks would still leave a lot of room for other stuff, like Charisma 5 [25], 25 points in other skills (and maybe more spells) [25], Energy Reserve 5 [15], and a useful 10-point advantage [10].

Now, this really charming Mage has a base of 20 for social skills, and could easily have a group of nearly devoted ritual casting assistants available! Their worst reaction result is poor, and average is between good and very good.

Now, as for the spells...

Mystic Mist, requiring Shield and Magery 2. Basic Cost of 1 means you could get something like 50-yard radius easily, enough to cover a large keep or a small castle entirely in it. Casting time of 50 minutes for a ceremonial version is way too long for GURPS Combat time scale, but is pretty doable in time scales of a typical siege. Duration of 10 hours is great, meaning you should be able to manage maintenance easily.

Watchdog, pretty much the same deal, but only for warning. Requires Sense Danger and Sense Foes. Ceremonial casting takes only 100 seconds.

Teleport Shield, cheaper to cast but with a duration of only 1 hour, requires your circle to use energy more often to maintain it. Only useful if expecting to get opposition to Teleport in, though. Requires Watchdog (yay!) and Spell Shield, Scryguard, Magic Resistance, (1 spell from 7 different colleges - got 2 of those so 5 more).

Spell Shield is pretty costly (Base cost of 3), but you should be able to protect a small keep with it, duration of 1 minute is the killer here, though!

Scryguard - keep all of your important people protected from enemy scrying! Duration of 10 hours is great, and cost is only 3/2 per person!

[Taneli]

The real killer are the spells on -penalties. You could probably get 3 or 4 effects on before needing to spend more energy to negate the penalties.

[Anaraxes]

Make the castle a no-mana zone. No one can use magic to attack it, so in that sense it's a perfect defense against magic. Mundane attackers only. Of course, the cost is that you also can't use magic to defend, or (probably worse) in the majority of your day-to-day life when you're not fighting off sieges. But if the castle builder thought that the offensive magic had the advantage, it might be a rational military tradeoff.

Works even better as a surprise, so the attacker shows up having planned on their magical abilities, only to be unexpectedly deprived of them, while the defender has planned for a fully mundane defense. But of course that only works once.

[Donny Brook]

I wonder if anyone has a prepared example of a fantasy keep, house or physical plant of any kind with ongoing or emergency defensive procedures and plans incorporating magic from any of the GURPS systems.

[hal]

Restormel Castle/Keep is, per Dan Howard's COMPACT CASTLES pdf, some 38 meters in diamter, or roughly 41.55 yards. Its max population rating is listed as 80 people, so we'll with with a support ratio of about 9:1 or 720 people overall. Assuming "People" means adults as well as children, I'm going to simplify this as being a keep that is supported by 720 people, or roughly 144 families. Since that is a really large village, this would work out reasonably well. I have one example of a village with a population of 110 families, so 144 isn't all too bad.

What that really means is that we're looking at a total of about 14.4 mageborn out of the original village population. Of that, 1/3rd is under the age of 15, so we're looking at roughly 10 adults (9.6 rounded up). Of those 10, roughly 75% will be servile (serfs) and the remainder will be freeborn. So call it 8 serfs and 2 freeborn.

Mind you, this is modeled off of Medieval England circa 1200 AD, but if you want me to include slaves as would have been appropriate during 1100 AD, I could go that route as well. The Domesday Book does give a general listing of Slaves by each village, but it appears that Restormal was built shortly after the Domesday Book was compiled and completed.

On the basic premise that the castle was built with outside funding in response to rebellion - rather than with personal resources initially, the entirety of the fortification would have been wood initially, and then built as a stone fortification. Over time, the stone aspects would have been erected and its strength as a major strategic fortification would have been solidified.

Your task, is to take a hard look at defending the fortification with magics such that not only does it constitute a massive defensive work for the defenders, but protects them against incoming attacks that could be mounted against the defensive works.

Much of those spells that are listed in GURPS MAGIC for 4e also include spells that were introduced in GURPS GRIMOIRE (which is now available as GURPS CLASSIC GRIMOIRE). Many of the spells contained in Grimoire include such spells as the Acid rain and such - which makes things considerably harder for the defensive works. None the less - as this is intended to be a Rules as Written exercise, it may be wise to include everything in GURPS MAGIC for 4e rather than cherry picking only those spells found in GURPS CLASSIC MAGIC.

It is my hope that the more we discuss this here, the more we can answer Donny Brook's question on what it would take to have a Fantasy Keep with ongoing or emergency defensive procedures for use with GURPS MAGIC. People are more than welcome to open up a similiar thread to this exloring other magic systems.

As Anaraxes has pointed out, one could drain mana throughout the entirety of the defensive area - but despite it being only a Magery 1 spell, a critical failure risks the permanent removal of 1 level of Magery from the spell caster. What price would you as a spell caster demand, if you were going to risk your magery on this spell casting? Player character mage that earns a higher than normal income for spell casting, will be required to take comfortable or higher levels of wealth for their 150 point characters.

In addition, while many could build "purpose built" characters, I would like to take a moment to ask that when you build your mage characters, that they actively be able to function within society. The spell lists should reflect the ability for the mage to make a living from spell casting as a whole, rather than be super specialized for the task at hand unless one wants to take the mindset that working at double pay as a mage for 6 months is equivalent for working at normal pay for 12 months (an argument I'd accept accually - as castle builders who were specialists often got paid handsomely - even if not fully employed all the time).

So, we'll prime the pump by saying that we have 10 mageborn, about a 50/50 mix between genders, about 8 who would have been born into "Serf" families with obligations to their lord.

I'm also going to go with the idea that instead of one BIG village of 144 families, we'll have two villages, one of about 100 families, and a smaller one of about 44 within easy walking distance of the fortification. If instead, this group would prefer to discuss this as a single village, I'm amendable to the idea. Simply put, this "exercise" will be intended to explore the possibilities, and decide how things will likely work out. My next post will discuss some other elements - curveballs or not, that is worth exploring...