Weapon and Armor Proficiency: Arcane trickster gain no additional proficiency in any weapon or armor.

Spells per Day: When a new arcane trickster level is gained, the character gains new spells per day as if he had also gained a level in a spellcasting class he belonged to before adding the prestige class. He does not, however, gain any other benefit a character of that class would have gained (improved chance of controlling or rebuking undead, metamagic or item creation feats, hit points beyond those he receives from the prestige class, and so on), except for an increased effective level of spellcasting. If a character had more than one spellcasting class before becoming an arcane trickster, he must decide to which class he adds the new level for purposes of determining spells per day.

Ranged Legerdemain (Su): Using his unique talents, an arcane trickster can perform one of the following class skills at a range of 30 feet: Disable Device, Open Lock, or Pick Pocket. Working at a distance increases the normal skill check DC by 5, and the arcane trickster cannot take 10 on the check. Any object so manipulated must weigh 5 pounds or less.

The arcane trickster can use ranged legerdemain only a certain number of times per day as determined by his level (see Table 3-4: The Arcane Trickster). He can make only one ranged skill check each day, and only if he has at least one rank in the skill being used.

Sneak Attack: This is exactly like the rogue ability of the same name. The extra damage dealt increases by +1d6 every other level (2nd, 4th, 6th, 8th, and 10th). If the arcane trickster gets a sneak attack modifier from another source (such as rogue levels), the bonuses to damage stack.

Impromptu Sneak Attack (Su): Once a day, the arcane trickster's unique combination of magical and rogue skills allows the arcane trickster to declare one melee or ranged attack the character makes to be a sneak attack (the target can be no more than 30 feet distant if the impromptu sneak attack is a ranged attack). The target of impromptu sneak attack loses any Dexterity bonus to Armor Class, but only against that attack. The power can be used against any target, but creatures that are not subject to critical hits suffer no extra damage (though they still lose any Dexterity bonus against the attack). At 7th level, the arcane trickster can use this ability twice a day.