Darklone said:
Domain wizards gain an arcane domain and one domain slot per available spell level. They learn their domain spell automatically when they reach a new level.
That's part of it.
An Arcane Domain is a list of 10 spells, 1 each of levels 0-9. These spells are automatically learned by the wizard when s/he reaches the level required to cast them, in addition to the 2 spells per level Wizards learn anyway. When casting the spells from this domain, the wizard receives a +1 caster level bonus to the effects, as well as being able to prepare 1 additional spell each day of each level, provided it is his/her Domain spell.
example: Fire Domain
0 - flare, 1 - burning hands, 2 - scorching ray, 3 - fireball, 4 - wall of fire, 5 - cone of fire (as cone of cold, but fire), 6 - summon monster VI (fire creatures only), 7 - delayed blast fireball, 8 - incendiary cloud, 9 - meteor swarm
A 5th level Wizard with the Fire Domain would have in his/her spellbook:
All 0-level spells, 3 + Int bonus 1st level spells, + 8 additional spells (2 each for levels 2, 3, 4, and 5) + burning hands, scorching ray, and fireball.
When preparing spells per day, the 5th level wizard would be able to prepare:
4 0-level spells + 1
flare; 3 + 1 (for Int) 1st-level spells +
burning hands; 2 + 1 (for Int) 2nd level spells + 1 scorching ray; 1 + 1 (for Int) 3rd level spells + 1
fireball.
When casting his/her spells, any casting of
flare,
burning hands,
scorching ray, or
fireball is cast at 6th level instead of 5th, regardless of whether it was prepared as a bonus domain spell or in a regular slot.
Note that some domain spells are not usually available to the wizard any other way (some are modifications of standard spells, like the
cone of fire mentioned above, but others are Cleric or Druid spells).
