Cumulative upkeep
(At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Illusions of Grandeur enters, you gain 20 life.
When Illusions of Grandeur leaves the battlefield, you lose 20 life.
If a player takes control of this card away from you, you do not lose 20 life because the loss of 20 life is a separate ability. That player is now subject to the loss.