Tuesday, December 22, 2009

Limits on Magic Use

As I may have mentioned, I've been working on a FATE-inspired, d20-informed gaming system. I'm designing it with D&D-style fantasy (loosely speaking) in mind. One of the problems that I'm running up against is that spellcasting is open to abuse.

In the system I'm designing, spellcasting is a skill. It effectively gives you the the ability to use rituals and some cantrip-like effects. When you cast a spell, you roll your skill. The margin of success or failure may make a difference - degrees of success can usually be spent, after the roll, on things like duration. You can buy additional sets of spells as feats. For instance (and I'm making this up as I go along), the feat Fire Magic I might let you use spellcasting to attack a single individual (and maybe a small area) with fire, protect yourself (and maybe others) from fire, start fires, and cause fires to flare up/die down.

I don't want to use a Vancian fire&forget system or import a spell point system. What I do want is something that will keep a spellcaster from casting the same spell over and over again. In combat, it might be nice for the fire mage to occasionally do something other than attack someone with fire, but that isn't my primary concern. I'm more worried about down time. Consider the fire mage who wants to protect himself from fire. What can be done to prevent him from rolling his spellcasting until he gets an incredibly good result?

Currently, I'm considering three options:
  1. Diminishing returns: If you cast a spell with a duration, any subsequent uses of that spell on the same target are made with a cumulative penalty. I'd have to play with the notion of duration here, since some spells that I'd want to include in this - like healing spells - are usually considered instantaneous.
  2. Extra cost: If you cast the same spell twice in a row, the second use costs a Fate Point (a fairly valuable meta-resource). The problem here is what "twice in a row" means. I don't want the healer to heal someone, shoot a fireball into the air, and heal that person again. That's silly.
  3. Fatigue/health cost: I'm generally not a fan of this, but the system I'm working with allows for some flexibility in interpreting damage. It will probably be an option for failed spells... and, coupled with option 1, that might be a significant deterrent.
Any other ideas?

7 comments:

David Dorward said...

How about having the spell roll be repeated for each attack it defends against?

Add something akin to a temporary aspect when the spell is cast.

"Protected from fire"

It then allows a spell roll to be made to set the defense value against each attack. It can be tagged for the usual reroll or +2 (and the caster gets to tag it once for free)

The aspect could be removed (e.g. if someone casts a counterspell) and will wear off at some point appropriate to the setting (The Dresden Files might set it to the next dawn, with shifts on the casting roll extending it)

Stuart said...

David,

I might do something like this, but I also want the degrees of success on a roll when a spell is cast to mean something - better protection (more free tags? more than the usual bonus?) or longer protection (variable duration.

This leads to the problem detailed in the post.

Why do I want the spellcasting roll to mean something? The power of spell casting types in this system is primarily defined by three things:

1. Applicable aspects - all spellcasters will have at least one. Those with multiple aspects will be able to invoke them more readily for bonuses and such.

2. Spellcasting feats - these are a character's spells, but these feats are primarily a measure of breadth rather than depth. Yes, there will be some trees with "higher level" effects, but it will be possible for a relatively inexperienced character to get one of these fairly quickly.

3. Spellcasting skill - In the system, skills are fairly expensive/difficult to buy. The skill is the closest thing to a level that the system has.

The way this should work out is that the same spell will tend to have very different effects when cast by characters with very different spellcasting skills.

Swordgleam said...

If what you're mostly worried about is buff spells, why not rule that each person can only take so much magic at once, or there will start to be ill effects? So the first time someone casts "resist fire" on you, you're fine, the second time, you start building up 'magic toxicity' but can probably still take a couple different kinds of buffs, by the third time in a row, you're reeling and can't handle any other magic for a while. Same with magical healing - the body can only be forced to heal faster than normal so much, after that, you risk long-term damage.

Stuart said...

That's an interesting way of looking at it. Hmmm...

Emerson Harris said...

What about a time-limit / increase in DC hybrid. Every spell has a "Cooldown," and every time you use the spell within the cooldown, the DC increases by 1 or 2 or whatever?

Phillip said...

Hmm...in my homebrewed magic system I treat magic as a finite resource. Mages search for and acquire "nodes" to power their spells. This system is an adaptation of the classic chinese elements table. Each elemental node has an individual energy rating and recharges at a fixed rate with wizards weaving differing elemental nodes together for varied effects.As I am the one that sets the charge rate/availability of these nodes, I have all the dials and switches that I need to control abuse. While player wizards have a lot of opportunity to be creative with their magic, they are also aware that there are limits to their power.

biff-dyskolos said...

For practical spell limits I would start with stunts. Each spell is a stunt.
- You can take a simple spell (Rote, Cantrip ?) as a stunt. Example, Magic Missile is a skill substitution (Magic for Archery or Guns). It doesn't cost anything to cast it, just Archery.
- You can take a complex or flexible spell as a stunt like Universal gadget, spend a FATE point to set or reset the spell (Add advances to it). Depending upon the power of the spell further restrictions may be necessary.
- You can take a very complex rituals as stunts. Similar to the Universal Gadget Spell above but the complexity is so high that you will need to make multiple rolls, additional casters, special materials to get enough shifts to create the effect.

Depending upon the power of the spell, FATE points may be used as a further limit on casting. A game called Mortal Coil (preview) uses several point pools, similar to FATE points, but you can use them in different ways
- You can Commit a point. A Committed FATE point is considered Spent for that scene. At the end of the scene, after a period or rest, you regain your Committed FATE points. This is similar to clearing your stress track.
- You can Spend a FATE point as per usual.
- You can Sacrifice a FATE point. This is like Spending an FATE point and loosing a point of Refresh.
This mechanic would allow you to use FATE points as a control that is proportional to the power of the spell.

A simple spell (see Magic Missile above) may be safe and reliable but complex and powerful spells may not be. A Fireball is powerful, it is a ranged attack, deal stress to every on in the zone, has a blast (add the aspect "Prone" to everyone in the zone), add the aspect "On Fire!" to flammable objects in the zone. When you cast it, opponents can try to dodge or dive for cover (Magic vs. Athletics). You have to beat their defence to deal stress. Also, the same roll has to beat the difficulty or level of the spell or the caster takes stress and possible consequences. You can rationalize this in several ways. The caster tried to channel too much power and got hurt, or paradox backlash.

A difficult spell may have "Material Components" aspect to reduce its difficulty. After casting such a spell your opponents could Compel that aspect for you to be "Out of Components". The caster has to spend a FATE point to buy off the compel or they can't cast the spell again until they can restock their components. This is similar to the "Out of Ammo" aspect on Slug Throwers in Diaspora.

A more serious issue with spell casting is Niche Protection. A Caster can steal the cool of other characters by using spells to duplicate their abilities, this sucks for the other players. Some systematic limits like those above may solve this problem or you may want to use group consensus. Casters can't do anything that the majority of players don't like.