Here's an 11th level elf assassin. Like Blackdirge, I used 32 point buy and equipped her with normal NPC value gear.
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Kasal Ophensa, female elf Brd5/Asn6; CR 11; ECL 11; medium-size humanoid (elf); HD 11d6; hp 43; Init +8 (+4 Dex, +4 Improved Initiative); Spd 30 ft; AC 17 (+4 Dex, +2 bracers, +1 ring); Atk +8/+3 melee (1d4+1, 19-20/x2 crit +1 dagger) or +13/+8 ranged (1d8+2, x3 crit +1 composite longbow); SA sneak attack +3d6, death attack; SQ elf traits, bardic music, bardic knowledge, poison use, uncanny dodge (Dex to AC, can’t be flanked), +3 saves vs. poison; AL NE; SV Fort +3, Ref +13, Will +5; Str 10, Dex 18, Con 10, Int 14, Wis 8, Cha 20.
Skills (84 points): Bluff +15, Diplomacy +13, Disguise +15, Gather Information +15, Hide +14, Innuendo +6, Listen +6, Move Silently +14, Perform (harp, pan pipes, dance, flute, ballad, drama, storytelling, lute, chant) +14, Sense Motive +9, Spot +6.
Feats: Point Blank Shot, Precise Shot, Rapid Shot, Improved Initiative.
Bard Spells Known (6/5/4, DC 15 + spell level): 0 - dancing lights, daze, flare, mage hand, open/close, prestidigitation; 1st - charm person, expeditious retreat, feather fall, mage armour; 2nd - detect thoughts, enthral, hold person.
Assassin Spells Prepared (-/2/2/1, DC 12 + spell level): 1st - change self, obscuring mist; 2nd - darkness, undetectable alignment; 3rd - invisibility.
Elf Traits (Ex): Immune to sleep and similar magical effects, +2 on saves vs. Enchantment, low-light vision, proficient with rapier and composite longbow, +2 to Listen, Search and Spot (already figured into skills above).
Bardic Music: Eleven times per day, Kasal may use her musical abilities to create magical effects. She is capable of inspiring courage, performing countersongs, fascinating creatures, inspiring greatness, and implanting suggestions in already fascinated creatures.
Bardic Knowledge (Ex): Kasal may make a special bardic knowledge check with a bonus of +7 to see whether she knows some relevant information about a variety of topics.
Sneak Attack (Ex): Whenever Kasal is able to successfully damage an opponent who is denied their Dexterity bonus to AC, or when she flanks an opponent, she is able to strike vital areas for an additional 3d6 points of damage. She can only apply this extra damage with ranged weapons if her target is within 30 feet.
Death Attack (Ex): If Kasal studies her victim for 3 rounds and then makes a sneak attack within the next 3 rounds with a melee weapon that successfully deals damage, the sneak attack may also paralyse or kill the target (Kasal’s choice). A victim who fails their saving throw (Fortitude DC 18) against the kill effect dies. If the saving throw fails against the paralyse effect, the victim’s mind and body become enervated, making him or her completely helpless and unable to act for 1d6+6 rounds.
Poison Use (Ex): Kasal is trained in the use of poison and never risks accidentally poisoning herself when applying poison to a blade.
Possessions: +1 dagger, +1 composite longbow, +1 arrows (20), cloak of charisma +2, bracers of armour +2, ring of protection +1, hat of disguise, masterwork harp, dark reaver powder, purple worm poison, black lotus extract, giant wasp poison.
Kasal Ophensa is an extremely beautiful elven woman with lustrous black hair and seductive green eyes. Even her considerable outer beauty could not mask her hideous soul, and she was exiled from her elven community for her cruel and vicious tendencies. She was in fact more than happy to leave her homeland, and wandered across the lands in various cities and towns. She now operates as a skilled assassin, and she undertakes her murderous missions with sadistic glee and anticipation.
Kasal prefers to use subtle means of destroying her marks rather than straight-out confrontation, in part because she is somewhat frail and lacking in combat ability, and also because she is a coward at heart and fears putting her precious skin in the line of fire. Kasal’s favoured method of assassination is to seduce her victim and slay them when they are alone. She is also very skilled in the use of poison.
While Kasal does try to avoid combat, if pressed she can fight. She usually uses her magical abilities, whether her spells or her bardic songs, or fires from a distance with her bow. She only closes to melee if there are others with her, or her target is already severely weakened. She will then attack with her dagger, which is invariably poisoned (Kasal’s favoured poison is purple worm poison, but she has been known to use others).