College of Metal

You are one of the few and proud inducted into the College of Metal. Those in this college wade into battle clad in heavy suits of armor, weapon ready to be brought to bear. They are like rolling thunder crashing through the battlefield with booming voice and cacophonous performance.

Heavy Metal

You gain proficiency with greataxes and heavy armor.

By performing a ritual over the course of an hour, you can forge a Slayer Axe by fusing a lute and greataxe together with lightning magic.This weapon appears to be made from metal and makes an unusually synthetic sound. You can use it as a lute, a spellcasting focus, or a greataxe.This weapon counts as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage. When you attack with this weapon, you can use your Charisma modifier, instead of Strength or Dexterity, for the attack and damage rolls.

You may only create one Slayer Axe at a time. If you a separated from your Slayer Axe for more than 24 hours, or if anyone but you attempts to use the Slayer Axe, the weapon's inert lightning magic will overload and render the weapon shattered beyond repair - magical or otherwise.

Rock Hard

Starting at the 3rd level, you have learned to strike hard and rock even harder. A creature that has a Bardic Inspiration die from you can use it's reaction when hit by an attack to roll that dice and reduce damage taken by the amount equal to the result of the die roll.
Additionally, when you hit a creature with a melee attack, you can cause a tremendous sound to erupt from your weapon. You roll a Bardic Inspiration die, dealing additional Thunder damage equal to the result of the die roll plus your Charisma modifier (minimum 1) to that creature.

Thunder Rolls

At 6th level, you know the Thunderclap cantrip as well as the Thunderwave and Shatter spells. These don't count towards your spells known.
Additionally, when you reduce a creature to 0 hit points or score a critical hit, you can case Thunderclap, Thunderwave, or Shatter as a Bonus Action. You must still expend a Spell Slot as normal.

Symphony of Battle

Starting at the 14th level, you can unleash a performance the likes which few have ever experiences. As an Action, you and and all creatures of your choice within 100 feet that can hear gain a Bardic Inspiration die. These are not taken from your Bardic Inspiration pool.
Additionally, hostile creatures that can hear within 50ft of you must make a Constitution saving throw against your Spell Save DC. On a failed save, they suffer 8d8 of Thunder damage and are Deafened. On a successful save, they take half as much damage and are not deafened. Once you use this feature you may not do so again until you complete a long rest.