The Ender Dragon is the vanilla boss mob found in The End. While most Ender Dragon information can be found here, there are a few new variables added to the mix when it comes to taking on the Ender Dragon. With the Divine mobs Ender Spider, Ender Watcher, and Ender Triplet added into the world, fighting the Ender Dragon is a lot more difficult than fighting him in vanilla. Knowing how each enemy operates will help the player understand what to do in specific situations, and understand the new precautions that must be taken in order to survive. That said, here's a breakdown of how The End will treat you during your battle.
Mobs, mobs, and more mobs: The End is now not only covered on the ground with Enderman, but Ender Spiders, Ender Watchers, and Ender Triplets. Avoiding eye contact is crucial with every ground mob in The End, for eye contact will make the mob you looked at hostile. One way to do so is to wear a Pumpkin on your head. If worn, looking at any Ender mob will not provoke them to attack. Ender Triplets are already hostile.
The Skies: Ironically enough, compared to the DivineRPG mobs, the Ender Dragon is relatively weak, especially if you have diamond armor or higher equipped, so damage output from the Ender Dragon isn't as much as a worry compared to the new mob roaming the skies in The End. The Ender Triplets are easily the most threatening mob in The End. Automatically hostile, firing explosive fireballs from a long range, like Ghasts, and too high to reach, this mob will be the bane of your existence in The End fighting the Ender Dragon. If you don't know anything about this mob, refer to the link above for more information before continuing on.
The fight: The battle with the Ender Dragon consists of vanilla strategies, tied together with DivineRPG strategies and precautions. Having a bed along with multiple bows and arrows just outside of The End is the best way to start, and if you have any armor, Eden or lower, then leaving it in a chest outside of The End is advised until either all of the Ender Crystals are destroyed or the Ender Dragon itself, since dying is almost inevitable until you have an understanding of the mobs and area.
As per norm, taking out the Ender Crystals that replenish the Ender Dragons health is crucial to start with, so having a Bow with arrows on hand is the best way to start. To avoid the Ender Dragon and Ender Triplet explosions, staying in a constant sprint will increase the longevity of your time in The End. Throughout The End, having multiple holes in the ground or safe havens is recommended to recover from heavy damage from Ender Triplets or to recover hunger. Once all of the Ender Crystals have been destroyed, the fight gets a little easier, since the new focus is the Dragon. While you will be spending most of your time running even if the Ender Dragon is nowhere in sight, a player can take advantage of the projectiles being fired from the Triplets since they can also hit the Ender Dragon. A direct hit on the boss will do massive damage, so a pattern typically happens everytime you fight it. You sprint, you get a shot in with a ranged weapon, you sprint some more, the Ender Dragon gets caught in the crossfire from the Triplet shots, you take another shot, you take cover to restore hunger, and repeat until the dragon is dead. The fight, of course, will vary from person to person, but as long as players have an idea of how the terrain, boss, and mobs work, they can get a better understanding of the fight. Again: dying is almost inevitable, so leave any valuables at home before you can confidently walk around in The End.
There is, however, another strategy. If you take in Bedrock Armor, it'll protect you from the ender triplets entirely, and the only thing that they can do to you at this stage is make you take fall damage, but that's nothing compared to the death of the ender dragon. It's also recommended that you bring a weapon like the Bowhead Anchor for the crystals. If you want to melee the ender dragon, then you should take a weapon such as the Frozen Maul or the Corrupted Maul. Since these weapons are semi-easy to get, and extremely powerful for such easy weapons to get, they are recommended for any time in the early game adventures.