The Enhancer room you can find if you step opposite Lost City bank through the red portal there.
With the Enhancer you can upgrade weapons, magery spellbooks and Necrobooks for now.
On Weapons it will upgrade min. & max. Base damage per 1 each success, so benefit you will do more dmg on weapons.
On Magery Spellbooks following Spells benefit from enhancing:
earthquake, mind blast, heal, magic arrow, fire field, lightning, mana drain, harm, chain lightning, flame strike, meteor swarm, energy bolt, explosion, fireball the bonus only works if the book is equipped.
On Necro Spellbooks following spells benefit from enhancing pain spike, poison strike and wither the bonus only works if the book is equipped.
After entering the red portal you will be teleported to the enhancer room.
Go near any of the 4 soul forges there and doubleclick it.
A window will pop up then you click the blue bottom and select the weapon or magery Spellbook you wish to upgrade.
After you have selected your item just click on the anvil sign to upgrade your item.
To close the window when you are done click cancel.
You will see on the left side of the window your chance of success right to it how many Badge of Slaying it will cost you.
You can upgrade any weapons minimum and maximum weapon damage by 1 if you succeed.
If you have 3 times succeeded on enhancing a weapon and you fail it will go dow by 1.
The chance of a successful upgrade goes down with the number of upgrades the item has already archieved.
1-3_____50% Success chance
4-6_____40% Success chance
7-9_____30% Success chance
10-12___20% Success chance
13-??___10% Success chance
As higher you enhance a weapon it will show you also by color at weapon damage from low WHITE > GREEN > BLUE > PURPLE > ORANGE high You will never lose or destroy the item you can only lose BoS and many of them. Luck or beeing stuffed has no effect on the success chance it is only real luck like on a gambling stone. There is no upper limit so far how often you can upgrade if you just have the badges of slaying for it.