The Boots are one of the Secret Items that enhance the abilities of the three characters. They decrease damage from hazardous surfaces and spikes by 25%. Even if the spikes are on the ceiling or walls and don't make contact with the character's feet, the Boots still reduce the damage dealt. They can be equipped by the Knight, the Thief, and the Wizard.
They are found in the Forsaken Dungeons near the end of the level. Enter the room with the three folding platforms after the fight with the skeleton boss and jump into the wall on the right to find the chest containing the Boots. When found they will automatically be placed in the Inventory Menu.
A complete list of the Secret Items can be seen in the Inventory Items page.