It's rare that two mages 'battle' face-to-face in D&D, despite plenty of instances in film and story. I believe this is mostly due to the all-or-nothing nature of spells - it's first-to-the-draw wins, with the other fellow converted to a smoky cloud, stone statue or similar. Magically defensive spells are rare, and often very specific - a Shield spell blocks only Magic Missiles, for instance, while Anti-Magic Shell and Globe Of Invulnerability are only available to higher-level casters. Most of the time it's better to just try and do away with the enemy before he does likewise with you. The following system attempts to add more to-and-fro into spell duels, and also allow lower-level wizards a little more longevity in those situations.
The central idea is that, by expending a memorised spell 'slot', a targeted wizard may be able to counter and nullify an incoming spell.
The target needs to use a spell slot of equal or higher level than the incoming spell, and must be able to begin countering before the enemy spellcaster completes their spell's Casting Time. Both casters then continue 'casting' until the attacking spell is completed - in both cases the usual opportunities for losing a spell through attacks and jostling apply. In order to counter a spell, the defending mage must be within its intended area of effect.
This system assumes that defending wizards can, in some fashion, sense the level of power of spells that others are beginning to cast; a kind of premonition of the energies as it gathers.
The defending wizard should describe how their chosen spell 'slot' is being expended to try and counter, for added colour and possibly a small bonus to the roll (see below). For example, a Mage Hand spell might be used to 'bat away' incoming Magic Missiles, or a Sleep spell used to cause the attacker to become dazed and lose concentration at a vital moment.
Once the incoming spell is cast, the two casters make rolls on 2d10 + their Caster level + 1/Int over 14, highest succeeds. A successful counter entirely nullifies the incoming spell, preventing it from affecting any of its targets.
Whatever happens, both casters expend the appropriate spell slot.
Note that these rules only apply when both attacker and defender are using arcane, non-priestly spells. It's not possible to counter a spell cast via a wand, staff or the like, although spells cast from a scroll can be countered, in which case the caster level of the original writer should be used in the roll above, with the scroll reader's Int score.
2nd Edition has an oddly truncated and piecemeal system for spell 'components'; Verbal, Somatic and Material, which has always felt to me like the beginnings of a good idea. 3rd Edition adds in a few more, including an XP cost for casting certain powerful magics. As usual, what I've ended up with is a mixture of the above with some ideas from Ars Magica and my own:
There exists a spell called Enchant a Focus, given below, which allows a wizard to create a permanent object that takes the place of most Material Components for their spells. The enchantment takes time and expense, and (importantly), is a strictly one-way deal - once a wizard has chosen to use a focus, they can't then abandon it. There are a few basic consequences:
- The wizard no longer needs a Material Component to cast most spells; the focus takes their place, as long as it is to hand. There are exceptions for particularly expensive and unique components.
- Spells that require a Somatic Component are cast by gesturing or pointing appropriately with the focus, and Touch ranged spells are cast by touching the target with the focus.
- If the wizard loses their focus, they are unable to cast any spell that needs a Material Component (except Enchant a Focus itself) until they create a replacement.
- Dispel Magic cannot harm a focus. Mordenkainen's Disjunction can render one inert, however.
- The wizard gains one extra spell memorisation 'slot' for spell levels 1 - 4 (if they're also a Specialist Wizard, the extra spell slots stack).
Enchant a Focus
1st lvl All Schools
- Casting Time
- See below
- Area of Effect
- One object
- Saving Throw
A chosen focus is usually highly individual to the caster, but it is always a valuable and well-crafted object. Typical foci include staves, daggers or knives, gloves, hats, cloaks, phials, lanterns and so on. Usually they're portable and not too bulky, but a non-travelling wizard might prefer an object more difficult to steal, like a cauldron or throne. In any case, the value of the object must be at least 100gp for each casting level used through it. A wizard's focus object is unique, and multiple copies of a foci cannot be created (there may be exceptions for certain magical societies - see below).
The time taken to create a focus is at least 2 weeks for each casting level used through it, during which time the wizard must work continuously with the object, carving and embellishing it with mystic symbols, valuable metals and gems and rare substances - the focus will always have the wizard's personal mark or rune upon it, which may be recognisable by those in the know.
This spell must be repeated if a wizard gains another casting level after choosing to use a focus - in this case the cost and time required is 100gp and 2 weeks.
If a focus is lost or destroyed, the wizard can create another one by re-casting this spell and taking the time and expense required.
Certain magical societies, guilds or circles of wizards may use objects that are so similar that they can use each other's foci. This may become known by their enemies and used as a point of weakness.