Boomerang master

you have mastered the technique of the boomerang, you've studied for hours to perfect your boomerangs effectiveness

spellcasting

you have started using magic to improve your boomerangs damage and effectiveness

you have 2 spell slots at level 3, 3 at level 7, 4 at level 10 and 5 at level 15.

you can cast these spell how ever many times you choose as long as you have the spell slot

Spell imbuement

you've learned to imbue a spell into your boomerang that activates on impact.

you can imbue any evocation cantrip from the wizard spell list onto your boomerang, it takes 1 action to do and the spell is cast once and can only be cast again when you imbue the cantrip again, the ability score used for the spell is your dexterity

Boomerang expert

you have become extremely talented in all things boomerang

Boomerang enhancements

you add some extra things onto your boomerang

Boomerang storm

you release a flury of boomerangs

composite boomerang

you can stack abilities (within reason) from previous levels as much as you want (infinite imbuements, infinite enhancements)

master craftsmanship

when you craft a boomerang it always gains the benefits of a natural 20 and on an actual natural 20 the boomerang is almost indestructible, has a range of 120 feet and does 1d6 damage naturally. As an action you can create a single use boomerang.

boomerang aura

you create a surround flurry of boomerangs