Weapon and Armor Proficiency: Bladesingers gain no proficiency with any weapon. They gain proficiency with light armor but not with shields.

Spells per Day: At every level gained in the bladesinger class except the first, the character gains new spells per day as if she had also gained a level in an arcane spellcasting class she belonged to before adding the prestige class. She does not, however, gain any other benefit a character of that class would have gained, except for an increased effective level of spellcasting. If a character had more than one arcane spellcasting class before becoming a bladesinger, she must decide to which class she adds the new level for purposes of determining spells per day.

Bladesong (Ex): While wielding a longsword or rapier in one hand (and nothing in the other), when a bladesinger successfully hits an opponent in melee, at the end of her turn, she may enter a complex dance that blends swordplay and magic, known as a bladesong. In a bladesong, she gains a dodge bonus to Armor Class equal to her Intelligence bonus. This bonus stacks with any other dodge bonus and Swashbuckler’s Uncanny Defense feature. She also ignores arcane spell failure chances when wearing light armor. If the bladesinger wears medium or heavy armor, she loses all benefits of the bladesong. A bladesong lasts for number of rounds equal to her rank in Perform (Dance). At the end of the a bladesong, a bladesinger is fatigued for the duration of the current encounter. She may only enter bladesong once per encounter.

Lesser Spellsong (Ex): When wielding a longsword or rapier in one hand (and nothing in the other), a bladesinger of 2nd level or higher can take 10 when making a Concentration check to cast defensively.

Bonus Feats: At 2nd, 5th, and 8th level, a bladesinger gets a bonus feat. These feats must be drawn from the following list: any sudden metamagic feat, Combat Reflexes, Improved Critical (longsword or rapier), or any feat that has Mobility, or Combat Expertise as a prerequisite.

Song of Celerity (Ex): During bladesong, if a bladesinger successfully hits an opponent in melee, a bladesinger of 2nd level or higher may quicken a single spell of up to 1st level, as if she had used the Quicken Spell feat, but without any adjustment to the spell's effective level or casting time. Casting a swift action spell does not provoke an attack of opportunity. She may only use this ability when wielding a longsword or rapier in one hand (and nothing in the other). This ability improves at 4th, 6th, 8th, and 10th level, allowing a bladesinger to quicken up to 2nd, 3rd, 4th, and 5th level spell, respectively.

Song of Fury (Ex): While in a bladesong, when a 3rd level bladesinger makes a full attack with a longsword or rapier in one hand (and nothing in the other), she can make one extra attack in a round at her highest base attack bonus, but this attack and each other attack made in that round take a -2 penalty. This penalty applies for 1 round, so it also affects attacks of opportunity the bladesinger might make before her next action.

Greater Spellsong (Ex): A bladesinger of 5th level or higher gains +4 dodge bonus to Armor Class until beginning of her next turn if she casts a spell during bladesong. Casting more than one spell do not grant additional bonus to AC.