Minecraft wiki entry for Player_versus_Player, associated text: If you are somewhere where strafing is impossible and you are not in water or hitting someone up a mountain, then jump, hit, and block at the same time. Spam the right and left click buttons at the same time. This will make you take a lot less damage while still dealing good damage to your opponent. If you are on a mountain and someone is repeatedly hitting you, you should jump over them, and then they will be at a higher elevation, so the fight will be turned in your favor.