Trumps of doom

Book 6 of the Chronicles of Amber. Merlin, son of Prince Corwin, is finishing up his education on Shadow Earth, and wrapping up a few loose ends. For example, why does someone attempt to kill him, every April 30th? The latest attempt leads him to the loss of an old love, a strange deck of Trumps, and a reconnection with an old friend. But all roads lead to Amber, and the mystery leads him into further danger....