Super Charging Enchantments but with a cost

By using a new type of anvil, (crying obsidian?) you could combine max level enchantments together to get one 1 tier higher. (Sharpness VI etc). The catch is that every supercharged enchantment comes with a random curse being bestowed on an item.

This would require the new anvil and several new curses for variety.

For example, a few curses that could be added:

Curse of Darkness: At night, visibility is reduced dramatically

Curse of Slowness: The wearer's movement speed is lowered

Curse of Leeching: Every few times you use a tool / weapon, a shank of hunger are used up.

Curse of Dysfunction: There is a chance for the item not to have its desired effect.