Crystal Cog

The Crystal Cog is an item associated exclusively with adding an effect to weapons crafted through the Forging Interface.

Crafting
The item is crafted using 1 Life Crystal and 1 Mushroom at an Anvil.

Effect
Adding the item to the Effect Slot in the Forging Interface will result in your weapon sometimes healing you for 20 life on contact with enemies.

The formula for calculating the chance is:

60/aps/2000, where 'aps' is the attack speed in attacks per second.