Vengeance is a Lunar Spell requiring 94 magic that rebounds 75% of the damage of the next hit back to their opponent, similar to a ring of recoil or deflect curses. However, this effect will wear off once the player logs out. The player will also say "Taste vengeance!" when it is activated. Players may only cast vengeance once every 30 seconds.
Source: http://runescape.wikia.com/wiki/Vengeance
3 Players casting Vengeance
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