Smite was the highest level prayer until the July 2007 introduction of Chivalry and Piety. When active, attacking another player will cause one of their prayer points to be drained for every 150 damage done. Smite is a popular prayer among player killers because it is used to prevent their opponent from using the Protect Items prayer, as well as protection prayers. Soul Split, a high level ancient curse that requires 92 prayer to use, offers a similar prayer draining ability as well as its widely known life stealing attribute.
In 2011 the info was changed around the time of the Wilderness Referendum when the mouse is hovering over the prayer, it now reads, "Opponent's Prayer stat is drained according to how much damage is done" instead of "1/4 of damage done is removed from opponent's prayer".
Before the Evolution of Combat update, Smite was more powerful than Soul split, draining 1 prayer point for every 4 damage done, compared to Soul Split's 1 prayer point for every 5.
Smite can also have a chance of canceling the protect item when the opponent dies while the protect item prayer is in place