Bladesong. As a bonus action, the bladesinger gains the following benefits:

• +5 Armor Class.
• Walking speed increases by 10 feet.
• Advantage on Dexterity (Acrobatic) checks.
• +5 bonus to concentration checks.
  The bladesinger starts the combat with Mage Armor and Bladesong

Spellcasting. The bladesinger is an 12th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). The bladesinger has the following wizard spells prepared:

Cantrips (at will): booming blade, fire bolt, green-flame blade, mage hand, minor illusion, 

1st level (4 slots): charm person, mage armor, shield

2nd level (3 slots):  mirror image, misty step, see invisibility, suggestion

3rd level (3 slots): counterspell, dispel magic, haste, lightning bolt

4th level (3 slots): confusion, greater invisibility, vitriolic sphere

5th level (2 slots): telekinesis, wall of force

6th level (1 slot): tenser's transformation

Multiattack. The bladesinger makes 2 attacks with its Flametongue.

Flametongue. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage and 7 (2d6) fire damage.