Spellcraft (Int; Trained Only)
Use this skill to identify spells as they are cast or spells already in place.
You can identify spells and magic effects. The DCs for Spellcraft checks relating to various tasks are summarized on the table above.
Action: Varies, as noted above.
Try Again: See above.
Special: If you are a specialist wizard, you get a +2 bonus on Spellcraft checks when dealing with a spell or effect from your specialty school. You take a -5 penalty when dealing with a spell or effect from a prohibited school (and some tasks, such as learning a prohibited spell, are just impossible).
If you have the Magical Aptitude feat, you get a +2 bonus on Spellcraft checks.
Synergy: If you have 5 or more ranks in Knowledge (arcana), you get a +2 bonus on Spellcraft checks.
If you have 5 or more ranks in Use Magic Device, you get a +2 bonus on Spellcraft checks to decipher spells on scrolls.
If you have 5 or more ranks in Spellcraft, you get a +2 bonus on Use Magic Device checks related to scrolls.
Additionally, certain spells allow you to gain information about magic, provided that you make a successful Spellcraft check as detailed in the spell description.
The character can identify properties of a magic item.
Identify Basic Property of Magic Item: This use of the skill requires one round of inspection, and functions exactly as if the character had cast an identify spell on the item. A character can't attempt this on the same item more than once.
Identify All Properties of Magic Item: This requires one minute of inspection, and reveals all properties of a single magic item (including command words and charges remaining). A character can't attempt this on the same item more than once. If an item has different caster levels for different properties, use the highest caster level.
Quick Identification: A character can identify a substance or potion in the field as a full-round action, without an alchemical lab or any cost. The character can't retry this check (or take 20); if he or she fails, the character must identify the substance in an alchemical lab, as normal.
Source: SRD 3.5 Combined Skills