The player with high concentration is particularly good at focusing their mind.
Classes: Bard, Cleric, Druid, Favored soul, Monk, Paladin, Ranger, Sorcerer, Spirit shaman, Warlock, Wizard; Arcane Scholar of Candlekeep, Arcane trickster, Blackguard, Eldritch knight, Neverwinter Nine, Pale master, Red dragon disciple, Red Wizard of Thay, Warpriest
Requires training: No
Check: If a character takes damage while casting a spell or using a spell-like ability, they must make a concentration check versus a DC of ten plus the amount of damage dealt plus the level of the spell (metamagic does not count) being cast in order not to get distracted and suffer spell failure. All spells cast while entangled or in defensive casting mode must pass a concentration check of DC 15 on cantrips, DC 16 on lvl1 spells etc up to a DC of 24 on lvl9 spells. A character may also take a concentration check to avoid the effects of the taunt skill.
Special: A character with the Combat Casting feat gets a +4 bonus on Concentration checks made in defensive casting mode. Note that the Skill Focus feat for Concentration is arguably better since the +3 bonus it provides applies to all Concentration checks, not only those for defensive casting.
DnD 3.5 comparison
Concentration checks are also used for skills that would provoke an attack of opportunity in distracting circumstances as well as to avoid AoOs in a defensive manner.
- NWN's singleplayer gameplay meant that concentration was often required as it was possible for opponents to easily move past a spellcaster's limited allies to directly attack the character.