Can a caster help another one to make a craft contingent spell?

Question

The Craft contingent spell feat description says

Craft Contingent Spell Type: Item Creation
Sources: Complete Arcane Unapproachable East

You know how to attach semipermanent spells to a creature and set them to activate under certain conditions. Prerequisite: Caster level 11th. Benefit: You can make contingent any spell that you know. Crafting a contingent spell takes one day for each 1,000 gp in its base price (spell level x caster level x 100 gp). To craft a contingent spell, you must spend 1/25 of this base price in XP and use up raw materials costing one-half the base price. Some spells incur extra costs in material components or XP (as noted in their descriptions), which must be paid when the contingent spell is created.

The DMG, at page 215, says

Prerequisites: Certain requirements must be met in order for a character to create a magic item. These include feats, spells, and miscellaneous requirements such as level alignment, and race or kind. The prerequisites for creation of an item are given immediately following the item's caster level. A spell prerequisite may be provided by a character who has prepared the spell (or who knows the spell in the case of a sorcerer or bard), or through the use of a spell completion or spell trigger magic item or a spell-like ability that produces, the desired spell effect. For each day that passes in the creation process, the creator must expend one spell completion item (such as a scroll) or one charge from a spell trigger, item (such as a wand), if either of those objects is used to supply a prerequisite. It is possible for more than one character to cooperate in, the creation of an item, with each participant providing one or more of the prerequisites. In some cases, cooperation may even be necessary, such as if one character knows some of the spells necessary to create an item and another character, knows the rest. If two or more characters cooperate to create an Item, they must agree among themselves who will be considered the creator for the purpose of determinations where the creator's level must be known. (It's generally sensible, although not mandatory, for the highest-level character involved to bet considered the creator.) The character designated as the creator, pays the XP required to make the item. Typically, a list of prerequisites includes one feat and one or more spells (or some other requirement in addition to the feat). When two spells at the end of a list are separated by "or", one of those spells is required in addition to every other spell mentioned prior to the last two. For example, the prerequisites for a ring of three wishes are "Forge Ring. wish or miracle", meaning that either wish or miracle is required as well as the Forge Ring feat

1. Can two characters collaborate to create a contingent spell with this feat?

2. Will the contingent spell depend on the will of the character who puts the spell?

More specifically, I have a cleric and I want to buy a contingence with Antimagic Field. The condition is: if an enemy casts Mage’s Disjunction, the contingency is activated. However I also want to be able to interrupt the Antimagic Field. I thought that if my cleric casts the spell, he can also interrupt it later as he is the main spellcaster.

Answer 1

• Can one creature that possesses the feat Craft Contingent Spell from Complete Arcane (77) cooperate with another creature to create the contingent spell?

  Technically, probably not. That is, while the feat Craft Contingent Spell is a feat possessing the type item creation, that classification serves very few general purposes, and that classification isn't helpful here. Further, while the Dungeon Master's Guide says, "It is possible for more than one character to cooperate in the creation of an item, with each participant providing one or more of the prerequisites" (215), a contingent spell doesn't have per se prerequisites; the Craft Contingent Spell feat itself and the later description of contingent spells (CAr 139) says what's required to create a contingent spell, and those descriptions—sadly—fail to mention anything about a contingent spell's prerequisites proper.

  However, were this DM to allow the feat Craft Contingent Spell into his campaigns, this DM would nonetheless treat a contingent spell as if it possesses the prerequisites the feat Craft Contingent Spell and the spell that's to be made a contingent spell therefore allowing creatures to cooperate in a contingent spell's creation. To forbid such cooperation because of a technicality seems, to this reader, more oversight than intention.

• Can the created contingent spell depend on the will of the creator rather than the subject (if different from the creator) on whom the contingent spell is created?

  Probably yes. The rules governing the activation conditions of a contingent spell—like the rules for the activation conditions of the 6th-level Sor/Wiz spell contingency [evoc] (PH 213) on which the idea of contingent spells is based—are incredibly vague. This makes such activation conditions as powerful as the player's creativity and, similarly, as powerful as the DM will allow.

  However, the purchaser of a contingent spell should bear in mind that—in this reader's view, anyway—it's the contingent spell's creator who ultimately picks the contingent spell's activation condition, not the contingent spell's subject. Further, and not incidentally, this reader views the contingent spell's creator as also picking the spell to be made contingent—and the subject having no idea of what that contingent spell actually is until the creation process is completed and the contingent spell subsequently inspected. In this DM's campaigns, when contingent spells have been made available, a client must trust absolutely any contingent spell's creator lest the client be embarrassed, slain, or worse by a deceptive creator's resulting contingent spell!

• My PC wants to buy a contingent spell that will activate an antimagic field spell if my PC would be affected by an effect like the Mordenkainen's disjunction spell. Is this legit?

  Technically, probably yes. A contingent spell's activation condition can be anything the DM allows, and—as established by answers to this question—the condition for a contingent spell's activation may extend to perfectly predicting the future. Thus, with the DM's approval, a contingent antimagic field spell with an activation condition like the question describes would activate in the incomprehensible instant before the disjunction spell would have affected the subject.

• The antimagic field spell is dismissible. Who can dismiss an antimagic field effect that's created by the contingent spell, the subject on whom the contingent spell was created, the contingent spell's creator, both, or neither?

  The description of Contingent Spells, in part, says, "Once assigned to a bearer, a contingent spell cannot be transferred to another creature…," and, "A contingent spell is tied to the bearer’s body, alive or dead…" (CAr 139). While it's not crystal clear, combined, this DM would rule that it's only the contingent spell's subject who can dismiss the spell and not the contingent spell's creator (again, if the two are different). It seems reasonable to this DM that, like the creator of a magic sword having no control over that sword when its wielded by another, the creator of a contingent spell likewise has no control over a contingent spell after it's created on another.

---

Note: The Craft Contingent Spell feat is widely considered one of the game's most powerful—and, potentially, most broken—feats. Access to just the contingency spell is itself sometimes enough for a specialist wizard not to ban the school of evocation, for instance. And the feat Craft Contingent spell, instead of allowing a lone contingency spell, allows everyone who can afford the luxury to have a number of contingent spells present equal to their Hit Dice! This is so powerful that it boggles the mind, and it can fundamentally change the way the game is played after the feat's introduced to the campaign. For example, the feat's presence may mean that creatures that possess significant wealth—be they PCs or NPCs—just won't die and are teleported to safety instead. In such campaigns at high levels expect both sides to have at least one member lead with a greater dispel magic spell or a variant in hopes of eliminating contingent spells, and expect battles to cost thousands of gp as a result.