Redemption is a Prayer that, if active when a player's life points fall below 10%, will heal a number of life points equal to 25x of the player's Prayer level, instantly draining all Prayer points. The healing does not depend on how much prayer you have left, so it is advisable to use it when your prayer points are significantly low. If a player's life points drop from >10% to 0% in one hit, the healing effect will not activate due to the player dying before they could be healed.
The healing effect have a one minute cooldown. The prayer itself can still be activated regardless, to no effect until this cooldown wears off.
This prayer does not heal you in the same way as Rapid Heal, which accelerates the life point gaining process as long as the prayer is active. Redemption is a one-time healing to a predetermined amount of life points. Redemption only works if you are being damaged (poison counts) while already below, or falling below 10% health. If you have less than 10% life points and aren't being damaged by any means, it will not work (a hit that deals no damage will not trigger it).
Redemption takes effect
This prayer is used by people scamming and luring in the Wilderness. Telling you to bring only one item, then to turn on this prayer and use Protect Item. You use up all your prayer points and consequently, Protect Item is undone and you lose your most valuable item.