Wikipedia

Infernal cape

The infernal cape is the most powerful melee cape in terms of overall bonuses, awarded for defeating TzKal-Zuk in the Inferno. It surpasses its predecessor, the fire cape, boasting greater melee attack and strength bonuses, along with slightly higher defensive bonuses. In spite of this, it is still surpassed by the Ardougne cloaks 3 and 4 in stab attack and prayer bonuses, and by the mythical cape in crush attack.