"In the beginning, Rakanoth served Andariel, the Maiden of Anguish, with efficient brutality, for his touch may open up many painful wounds. He was also the warden of Izual during many long years that the angel suffered in Rakanoth's own Plains of Despair, but he has quit his realm unexpectedly in recent times."— Deckard Cain(src)
Rakanoth served as a warden to the imprisoned angel Izual, whom he guarded in the Plains of Despair - his own domain in the Burning Hells. He also fought in the Great Conflict, battling Tyrael on at least one occasion.
When Diablo incorporated the essences of the six other Great Evils through the Black Soulstone and became the all powerful Prime Evil, he emptied almost all of Hell's various realms in order to create a grand army for a massive assault on the High Heavens. Rakanoth was among those he summoned and was assigned the task of guarding the archangel Auriel holding her captive in the Library of Fate. However, the Nephalem managed to rescue the archangel by slaying Rakanoth in combat, thus bringing hope back to all of angelkind in their darkest hour.
Upon death, he has a chance to drop Hand of Despair.
Similar to Izual, he is also a heavy melee boss, but doesn't move as much. However, this makes him even more dangerous since his most damaging abilities are used when far away from the player. This puts each player at dilemma of either suffering heavy damage in melee or running around, facing the risks of ranged attacks.
On Torment difficulty, he has a hard Enrage timer, his Teleport Charge cooldown will be reduced to zero after 3 minutes.
- Blade Strike - basic melee attack, hits for average Physical damage.
- Teleport Charge - Rakanoth's iconic and most dangerous attack that can hit any player not within melee range (even within a few yards). Teleports towards the player, inflicting a heavy Physical damage hit (enough to one-shot a poorly armored hero). If it backstabs (i.e the target was not facing Rakanoth at the time of Charge), target is killed outright (technically, damage is increased to values beyond reasonable survivability), but abilities that are guaranteed to absorb an attack rather than damage can prevent this (for example, Wizard's Ancient Guardian Familiar at low health).
- Blade Cleave - more powerful melee attack, but takes more time to prepare and can be avoided.
- Volley - Rakanoth is paralyzed for 3 seconds, but while paralyzed, he will bombard an arc at long distance with missiles that deal average damage. Less effective at melee range, but causes Knockback.
- Summon Minions - summons two Soul Lashers. Used automatically every X% of health (depends on difficulty). Upon killing both, player receives a guaranteed Health Globe.
Rakanoth is one of the 7 Bosses of Diablo III to have an Uber appearance: The Vile Executioner, Vicious Blademaster. His Uber version sports no change in strategy whatsoever, but he fights alongside The Foul Desecrator, giving some strategies on him a bit more trouble than players would have fighting in Act IV.
- Rakanoth is the only demon that is not a Great Evils to be mentioned in the Prophecy of the End of Days ("and all Hope shall be swallowed by Despair").