per day/per-encounter spells (guessing)
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For caster classes, your highest level spells can be used once per day, and you have to re-prepare them as per normal to use them again.
Your next two levels of spells down can be used per encounter, and it takes 1 minute each to re-prepare them before they can be used again.
Spells three or more levels below your top spells can be used at-will.
Saves
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Base save is 10 + level + class bonus for Fort, Ref and Will.
The class bonus is a one-off bonus at 1st level. If you multiclass, you take the higher of the class bonuses.
e.g.
Fighter +2 Fort, +0 Ref, +0 Will
Rogue +0 Fort, +2 Ref, +0 Will
Ranger +1 Fort, +1 Ref, +0 Will
Cleric +1 Fort, +0 Ref, +1 Will
Wizard +0 Fort, +0 Ref, +2 Will.
Magic Attack Bonus
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There is also a MAB (Magic Attack Bonus). For full caster classes it is 1/1, for half caster classes (bard, ranger, paladin) it is 3/4 level, for non caster classes it is 1/2 level.
If you have a +x magic staff, it adds to rolls against Fort defence. If you have a +x magic wand it adds to rolls against a Ref defence. If you have a +x magic orb it adds to rolls against a Will defence.
multiple foes
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If targeting multiple foes, one magical attack roll is matched against all of their saves together.
Melee
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Full attacks disappear. Instead you add + half level (rounded down) to damage with all attacks.
Movement
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Charge attack is a standard action
Withdraw is a move action that doesn't provoke an AoO.
Crits
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Critical hits are scored on a 20 and do double damage. No confirmation roll required
Second Wind
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Once per day a character can gain 'second wind'. Recover hit points equal to either your Con score or 1/4 of your total hp, whichever is greater.