Several years ago, I compiled a list of "Caveats" for the Pen&Paper roleplaying magic system (ie, a ruleset for magic at the game table) presented in
GURPS Magic for GURPS 4th edition and wrote it down at gurpswiki.net, which was a growing fan-based GURPS wiki at the time. I have recently discovered that gurpswiki.net is no longer there, so I have dug up the text from the web archive (at archive.org) and have pasted it in here for future reference.
Magic 4e Caveats
GURPS Magic 4e offers many spells, some of which seem to be quite unbalancing, such as Earth To Stone, which allows a circle of about ten mages to take over Europe's entire medieval steel production. The following house rules solve these problems.
Creation and ennobling spells
The creation and ennobling spells are those spells which, well, create or ennoble something permanently. This is usually a problem for most game worlds, because it makes such things incredibly cheap and more mundane ways to produce them become obsolete. What follows is a solution to this problem.
General guideline: Any spell which permanently or instantaneously creates or ennobles something without using the enchantment rules has its duration changed to a more limited value, usually one hour. Materials that are consumed before the end of the duration time (such as food or water) work just like permanently created materials - unless the "consuming" is actually some kind of processing to create something permanent (thus, iron ore created with Create Earth would vanish after an hour even if processed into pure iron). If one actually wants to create something permanently or instantaneously, one has to use the enchantment rules- for the enchantment, apply a casting cost modifier as given below, usually x100, for a permanent creation or ennobling.
The following spells will thus have changed durations and new enchantment casting cost modifiers (list is incomplete; feel free to add problematic spells of the creation and ennobling type):
- Create Earth: Duration 1 hour, half cost to maintain. Casting cost modifier for creating earth permanently: x100
- Earth To Stone: Duration 1 hour, half cost to maintain. Casting cost modifier for permanently changing earth to stone or stone to metal: x100
- Essential Earth: Duration 1 hour, half cost to maintain. Casting cost modifier for creating essential earth permanently: x5000 (this will make the materials adamantium and orichalcum, which can be made from Essential Earth by using Earth To Stone on it about 30 times as expensive as more mundane materials, as given in Fantasy 4e)
- Copy: Duration 1 hour, half cost to maintain. Casting cost modifier to permanently Copy something: x100
- Create Water: Duration 1 hour, half cost to maintain. Casting cost modifier for creating water permanently: x100
- Create Food: Duration 1 hour, half cost to maintain. Casting cost modifier for creating food permanently: x100
- Create Ice; Duration 1 hour, half cost to maintain. Casting cost modifier for creating permanent ice: x100
- Create Air: Duration 1 hour, half cost to maintain. Casting cost modifier for creating air permanently: x100
- Essential Wood: Duration 1 hour, half cost to maintain. Casting cost modifier for ennobling wood to essential wood permanently: x100
- Zombie: Duration 12 hours or until next sunrise, whatever is lower, half cost to maintain. Casting cost modifier for enchanting permanent Zombies: x25
- Mass Zombie: Duration 12 hours or until next sunrise, whatever is lower, half cost to maintain. Casting cost modifier for enchanting permanent Zombie hordes: x25
- Timeout: Duration 10 hours of the caster's subjective time. Half cost to maintain. Enchantment is impossible in a timeout zone due to the strange repercussions this spell has on local mana.
Other spells with problems and solutions
- The Enlarge spell has no maximum size given. As a result, a mage could easily create a giant larger than the entire planet, or turn his world into a black hole, with less than 200 energy. This is obviously unbalancing. The best solution found so far is to limit the increase in SM to the level of the caster's Magery. Thus, a Magery 1 mage could increase the size to SM+1, a Magery 4 mage could increase it to SM+4, etc.