Weapon and Armor Proficiency: An assassin's weapon training focuses on weapons suitable for stealth and sneak attacks. Assassins are proficient with the crossbow (hand, light, or heavy), dagger (any type), dart, rapier, sap, shortbow (normal and composite), and short sword. Assassins are proficient with light armor but not with shields.

Sneak Attack: This is exactly like the rogue ability of the same name. The extra damage dealt increases by +1d6 every other level (1st, 3rd, 5th, 7th, and 9th). If an assassin gets a sneak attack bonus from another source (such as rogue levels), the bonuses on damage stack.

Death Attack: If an assassin studies his victim for 3 rounds and then makes a sneak attack with a melee weapon that successfully deals damage, the sneak attack has the additional effect of possibly either paralyzing or killing the target (assassin's choice). While studying the victim, the assassin can undertake other actions so long as his attention stays focused on the target and the target does not detect the assassin or recognize the assassin as an enemy. If the victim of such an attack fails a Fortitude save (DC 10 + the assassin's class level + the assassin's Int modifier) against the kill effect, she dies. If the saving throw fails against the paralysis effect, the victim's mind and body become enervated, rendering her helpless and unable to act for 1d6 rounds plus 1 round per level of the assassin. If the victim's saving throw succeeds, the attack is just a normal sneak attack. Once the assassin has completed the 3 rounds of study, he must make the death attack within the next 3 rounds. If a death attack is attempted and fails (the victim makes her save) or if the assassin does not launch the attack within 3 rounds of completing the study, 3 new rounds of study are required before he can attempt another death attack.

Poison Use: Assassins are trained in the use of poison and never risk accidentally poisoning themselves when applying poison to a blade.

Spells: Beginning at 1st level, an assassin gains the ability to cast a number of arcane spells. When he gain access to a new level of spells, he automatically knows all the spells for that level on the assassin's spell list. He can cast any spell he knows without preparing it ahead of time. Essentially, his spell list is the same as his spells known list. The assassin's spell list appears below.

To cast a spell, an assassin must have an Intelligence score of at least 10 + the spell's level, so an assassin with an Intelligence of 10 or lower cannot cast these spells. Assassin bonus spells are based on Intelligence, and saving throws against these spells have a DC of 10 + spell level + the assassin's Intelligence bonus (if any). When the assassin gets 0 spells per day of a given spell level (for instance, 1st-level spells for a 1st-level assassin), he gains only the bonus spells he would be entitled to based on his Intelligence score for that spell level.

Save Bonus against Poison: Assassins train with poisons of all types and slowly grow more and more resistant to their effects. This is reflected by a natural saving throw bonus to all poisons gained at 2nd level that increases by +1 for every two additional levels the assassin gains (+2 at 4th level, +3 at 6th level, and so on).

Uncanny Dodge (Ex): Starting at 2nd level, an assassin gains the ability to react to danger before his senses would normally allow him to even be aware of it. He retains his Dexterity bonus to AC (if any) regardless of being caught flat-footed or struck by an invisible attacker. (He still loses any Dexterity bonus to AC if immobilized.)

If a character gains uncanny dodge from a second class (such as a barbarian/rogue), the character automatically gains improved uncanny dodge (see below).

Improved Uncanny Dodge (Ex): At 5th level, an assassin can no longer be flanked, since he can react to opponents on opposite sides of him as easily as he can react to a single attacker. This defense denies rogues the ability to use flank attacks to sneak attack the assassin. The exception to this defense is that a rogue at least four levels higher than the assassin can flank him (and thus sneak attack him). If a character gains uncanny dodge (see above) from a second class (such as a barbarian/rogue), the character automatically gains improved uncanny dodge, and the levels from those classes stack to determine the minimum rogue level required to flank the character.

Hide in Plain Sight (Su): At 8th level, an assassin can use the Hide skill even while being observed. As long as he is within 10 feet of some sort of shadow, an assassin can hide himself from view in the open without having anything to actually hide behind. He cannot, however, hide in his own shadow.