Aluren, sometimes called Raisin Bran, is a blue-green-black combo deck heavily built around the card of the same name. The goal is to get Aluren into play with Cavern Harpy, Man-O'-War and Spike Feeder in hand. Playing Spike Feeder and removing one spike counter would gain 2 life. Then play Man-O'-War and bounce the Feeder. Then play Harpy and bounce Man-O'-War using its Gating ability and then return the Harpy with its second ability losing one life. This would be a total net gain of one life. This could be repeated endlessly for virtually infinite life as the combo could also be restarted at any point in time.
Once at a high amount of life, Wall of Roots would replace the Feeder, or Cloud of Faeries would replace Man-O'-War in the loop above, producing infinite mana which would later power a Stroke of Genius forcing the opponent to draw more cards than his deck contains, ending the game.
Vampiric Tutor, Brainstorm and Intuition were used in early versions to access the cards in the deck. However, this was rather secondary compared to Raven Familiar who could combo with Harpy enabling the deck to start its combo before either Man-O'-War or Feeder were even in hand. Wirewood Savage was used similarly to just draw cards until the combo cards were all in hand. When Vampiric left the format, it was replaced by Eladamri's Call and later Living Wish.
Later editions would replace Man-O'War and Spike Feeder by simply using Soul Warden instead which would already give infinite life with the Harpy alone by bouncing the Harpy itself to Gating. Soul Warden in turn was later replaced by Auriok Champion which was harder to kill. In the end, a Maggot Carrier would be repeatedly bounced with Harpy and played with Aluren. Meanwhile, the Warden would keep your life total at a steady high point while the opponent's life was draining.