From Melvor Idle

A template for quickly building prayer links with icons. For example, {{PrayerIcon|Mystic Might}} becomes Mystic Might (prayer).svg Mystic Might.

Adding a second argument allows you to override the text. For example, {{PrayerIcon|Augury|TURBO MAGE PRAYER}} gives Augury (prayer).svg TURBO MAGE PRAYER

For a complete list of options, please refer to Template:Icon.