Enchant Crossbow Bolt (Ruby) is a spell that allows Ruby bolts to be enchanted, making them Ruby bolts (e) and imbuing them with a special effect called Blood Forfeit. Blood Forfeit adds a chance to damage your opponent with an amount equal to 20% of their current hitpoints, capped at 100 damage. This effect also costs 10% of the current hitpoints of the player using the bolts. If the player does not have enough hitpoints to spare, this effect does not activate. These bolts are most effective against enemies with a large number of hitpoints and are often used in boss hunting.

This spell is available at Magic level 49, giving 59 experience. It requires 1 Blood rune, 1 Cosmic rune, and 5 Fire runes to cast.