Extended Trix deck
Trix was a blue-based combo deck which wants to Donate an Illusions of Grandeur to an opponent, causing them to sacrifice it when they can't pay the Cumulative upkeep cost and lose 20 life. Some versions of the deck used other colors to protect and search for the combo, such as black for Discard and tutors like Demonic Consultation and Vampiric Tutor. Necropotence was heavily used in this deck, and with Illusions also providing 20 extra life points, it also had significantly less of a downside.
Necropotence and Demonic Consultation were later banned from the format, but the deck lived on in one form or another for some time until Illusions of Grandeur left the format along with Ice Age.