You can buy a spell and cast it, voodoo dolls can took ~ 500dmg at level 21, u need 5+ in crafting, if you want to craft it. VD isn't immune to knockdowns.
You can upgrade bow with sextant and bowstring.
You have to read crafting thread more carefully.

Quote
[Crafting 2] Boosted Bow = Bow + Bowstring (+ Damage)
[Crafting 3] Boosted Bow = Bow + Sextant (+ Perception)
[Crafting 5] Boosted Apparel = Apparel + Ruby (Secrets of the Scroll IX) (+ Air, Earth, Fire, and Water Resistance. +5%(IL1) / +10%(IL2) / +15%(IL7) / +20%(IL12) / +25%(IL17).)
[Crafting 5] Boosted Weapon = Weapon + Tormented Soul (Secrets of the Scroll VII) (+ Strength + Dexterity)

I don't know how to upgrade hammer for additional dmg.