====== Casting Spells ======

Whether a spell is arcane or divine, and whether a character prepares spells in advance or chooses them on the spot, casting a spell works the same way.

===== Choosing a Spell =====

First you must choose which spell to cast. If you're a cleric, druid, experienced paladin, experienced ranger, or wizard, you select from among spells prepared earlier in the day and not yet cast (see Preparing Wizard Spells and Preparing Divine Spells).

If you're a bard or sorcerer, you can select any spell you know, provided you are capable of casting spells of that level or higher.

To cast a spell, you must be able to speak (if the spell has a verbal component), gesture (if it has a somatic component), and manipulate the material components or focus (if any). Additionally, you must concentrate to cast a spell.

If a spell has multiple versions, you choose which version to use when you cast it. You don't have to prepare (or learn, in the case of a bard or sorcerer) a specific version of the spell.

Once you've cast a prepared spell, you can't cast it again until you prepare it again. (If you've prepared multiple copies of a single spell, you can cast each copy once.) If you're a bard or sorcerer, casting a spell counts against your daily limit for spells of that spell level, but you can cast the same spell again if you haven't reached your limit.

===== Concentration =====

Table: Concentration Check DCs 
^ Situation	^ Concentration Check DC ^
|Cast defensively	|15 + double spell level|
|Injured while casting	|10 + damage dealt + spell level|
|Continuous damage while casting	|10 + 1/2 damage dealt + spell level|
|Affected by a non-damaging spell while casting	|DC of the spell + spell level|
|Grappled or pinned while casting	|10 + grappler's CMB + spell level|
|Vigorous motion while casting	|10 + spell level|
|Violent motion while casting	|15 + spell level|
|Extremely violent motion while casting	|20 + spell level|
|Wind with rain or sleet while casting	|5 + spell level|
|Wind with hail and debris while casting	|10 + spell level|
|Weather caused by spell	|see spell|
|Entangled while casting	|15 + spell level|

To cast a spell, you must concentrate. If something interrupts your concentration while you're casting, you must make a concentration check or lose the spell. When you make a concentration check, you roll d20 and add your caster level and the ability score modifier used to determine bonus spells of the same type. Clerics, druids, and rangers add their Wisdom modifier. Bards, paladins, and sorcerers add their Charisma modifier. Finally, wizards add their Intelligence modifier. The more distracting the interruption and the higher the level of the spell you are trying to cast, the higher the DC (see Table: Concentration Check DCs). If you fail the check, you lose the spell just as if you had cast it to no effect.

  ?? Injury: :: If you take damage while trying to cast a spell, you must make a concentration check with a DC equal to 10 + the damage taken + the level of the spell you're casting. If you fail the check, you lose the spell without effect. The interrupting event strikes during spellcasting if it comes between the time you started and the time you complete a spell (for a spell with a casting time of 1 full round or more) or if it comes in response to your casting the spell (such as an attack of opportunity provoked by the spell or a contingent attack, such as a readied action).

If you are taking continuous damage, such as from an acid arrow or by standing in a lake of lava, half the damage is considered to take place while you are casting a spell. You must make a concentration check with a DC equal to 10 + 1/2 the damage that the continuous source last dealt + the level of the spell you're casting. If the last damage dealt was the last damage that the effect could deal, then the damage is over and does not distract you. !!

  ?? Spell: :: If you are affected by a spell while attempting to cast a spell of your own, you must make a concentration check or lose the spell you are casting. If the spell affecting you deals damage, the DC is 10 + the damage taken + the level of the spell you're casting.

If the spell interferes with you or distracts you in some other way, the DC is the spell's saving throw DC + the level of the spell you're casting. For a spell with no saving throw, it's the DC that the spell's saving throw would have if a save were allowed (10 + spell level + caster's ability score).!!

  ?? Grappling or Pinned: :: The only spells you can cast while grappling or pinned are those without somatic components and whose material components (if any) you have in hand. Even so, you must make a concentration check (DC 10 + the grappler's CMB + the level of the spell you're casting) or lose the spell. !!

  ?? Vigorous Motion: :: If you are riding on a moving mount, taking a bouncy ride in a wagon, on a small boat in rough water, belowdecks in a storm-tossed ship, or simply being jostled in a similar fashion, you must make a concentration check (DC 10 + the level of the spell you're casting) or lose the spell.!!

  ?? Violent Motion: :: If you are on a galloping horse, taking a very rough ride in a wagon, on a small boat in rapids or in a storm, on deck in a storm-tossed ship, or being pitched roughly about in a similar fashion, you must make a concentration check (DC 15 + the level of the spell you're casting) or lose the spell. If the motion is extremely violent, such as that caused by an earthquake, the DC is equal to 20 + the level of the spell you're casting.!!

  ?? Violent Weather: :: You must make a concentration check if you try to cast a spell in violent weather. If you are in a high wind carrying blinding rain or sleet, the DC is 5 + the level of the spell you're casting. If you are in wind-driven hail, dust, or debris, the DC is 10 + the level of the spell you're casting. In either case, you lose the spell if you fail the concentration check. If the weather is caused by a spell, use the rules as described in the spell's description.

  ?? Casting Defensively: ::If you want to cast a spell without provoking any attacks of opportunity, you must make a concentration check (DC 15 + double the level of the spell you're casting) to succeed. You lose the spell if you fail.!!

  ?? Entangled: :: If you want to cast a spell while entangled in a net or by a tanglefoot bag or while you're affected by a spell with similar effects, you must make a concentration check to cast the spell (DC 15 + the level of the spell you're casting). You lose the spell if you fail.!!
  
===== Counterspells =====

It is possible to cast any spell as a counterspell. By doing so, you are using the spell's energy to disrupt the casting of the same spell by another character. Counterspelling works even if one spell is divine and the other arcane.

  ?? How Counterspells Work: :: To use a counterspell, you must select an opponent as the target of the counterspell. You do this by choosing to ready an action. In doing so, you elect to wait to complete your action until your opponent tries to cast a spell. You may still move at your normal speed, since ready is a standard action.

If the target of your counterspell tries to cast a spell, make a Spellcraft check (DC 15 + the spell's level). This check is a free action. If the check succeeds, you correctly identify the opponent's spell and can attempt to counter it. If the check fails, you can't do either of these things.

To complete the action, you must then cast an appropriate spell. As a general rule, a spell can only counter itself. If you are able to cast the same spell and you have it prepared (or have a slot of the appropriate level available), you cast it, creating a counterspell effect. If the target is within range, both spells automatically negate each other with no other results.!!

  ?? Counterspelling Metamagic Spells: :: Metamagic feats are not taken into account when determining whether a spell can be countered.??

  ?? Specific Exceptions: :: Some spells can counter other specific spells, often those with diametrically opposed effects.!!

  ?? Dispel Magic as a Counterspell: :: You can usually use dispel magic to counterspell another spell being cast without needing to identify the spell being cast. Dispel magic doesn't always work as a counterspell (see the spell description).!!