Opening, middlegame, and endgame?
I love the endgames. It's thrilling that at this phase of game, you or me is mated or not, and most of the pieces are gone in the endgame, so I must concentrate on how to mate my opponent with resting few pieces or how to prevent my being mated.
Deeper endgames I must concern how to promote my pawn and how to prevent my opponents promotion. Once I got my pawn to a queen, I can grip the winning, but it's always difficult to promote a pawn into a queen. Sometimes I must consider about stalemate. Anyway, endgames of chess is a white-knuckle thing for me and it's exciting.