Material Assimilator

You have discovered the ability to magically take in various materials, granting you armor, the ability to create weapons, and a few more unique effects. At level 3, you gain the ability to take in metal, stone, or wood as an action to gain special effects, a number of times equal to half your proficiency modifier per long rest. When active, you can create a weapon that deals 1d6 + your intelligence modifier as damage. You are proficient with these weapons and their rolls are tied to your intelligence modifier. At level 5 you gain an additional attack. At level 9, you gain the ability to create additional material, and launch it at enemy within 30 feet as a bonus action. Make a ranged spell attack against them, on a hit they take 2d4 piercing damage. At level 15, you learn to assimilate material quicker, and can now absorb and dislodge it as a bonus action. 

Material assimilation.

As an action, absorb 1/4th your weight in material to grant yourself special properties unique to that material type. 
wood: gain a 12 ac plus your dex modifier. You gain resistance to piercing damage, and vulnerability to slashing. While made of wood, you can cause branches to sprout all over yourself as an action,  like a tree. You can hear and see through the branches but others will perceive you as a tree unless they inspect you closely. You also can summon wooden clubs on your arms that deal bludgeoning damage. 

metal: you gain a 14 ac + half your dex modifier rounded up. You are resistant to bludgeoning, but weak to piercing. You also gain the ability to shape small or tiny objects out of the metal in your body, a number of times equal to your proficiency modifier. This can be done at any time, and even in an enclosed space, such as a finger in a key hole. You can also shape your arms into sharp piercing weapons. 

Stone: you gain a 17 ac, as well as resistance to slashing, but a weakness to bludgeoning. When hit with a melee attack,  you can command your armor as a reaction to make a melee spell attack against the one who hit you. On a hit, they take 1d4 piercing damage. You can make your arms into axe blades, dealing slashing damage.

Extra attack

You gain an extra attack 

Attack

You gain an extra attack 

Armor barrage

As a bonus action, create new material, and shoot at it at an enemy as a ranged spell attack. In a hit, they take 2d4 magical piercing damage. 

Quick Assimilation

You can assimilate and expel the required material much more quickly, now you can do so as a bonus action.