Minecraft wiki entry for Defeating_the_ender_dragon, associated text: The more crystals you have destroyed, the more often the dragon dives at the portal. When it's hovering over the portal, it is immune to arrow damage, and you are forced to use your sword. Here, get as many critical hits as possible, which deal more damage, and it is possible to get more critical hits when you have Slow Falling. It is also suggested to drink a strength potion because you can inflict more damage using the strength the potion provides.