When Marina Vendrell's Grimoire enters the battlefield, its first ability triggers, causing you to draw five cards.
Starving Revenant's second ability triggers five times.
Resolve the first Starving Revenant trigger, causing you to gain 1 life and an opponent to lose 1 life.
Marina Vendrell's Grimoire's second ability triggers, causing you to draw a card.
Starving Revenant's second ability triggers, causing you to gain 1 life and an opponent to lose 1 life.
Repeat from step 5.
Notes
This combo will result in you eventually drawing from an empty library, thus losing the game. It is highly recommended to have a way to stop the combo at instant speed or to otherwise stop yourself from losing the game.