Wyvern

A Wyvern is a flying, non-solid enemy, added and only available in the 1.1 update and after. It slightly resembles the face of a dog and the body of a serpent/dragon with hands and feet.

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It has a total of 4,000 health, and will only spawn after the player has defeated the Wall of Flesh, and also when the player is anywhere above 800 feet high (Or 300 feet above the Hallow). This enemy is a mini boss, and can be dangerous for players not wearing good armor, as the head can hit an undefended player up to 90 damage, while the body only does about 40. When a Wyvern dies, it may glitch and still show its body, if a player touches it, the player gets hurt, and if they hit it, it disappears.

Option 1
A good strategy will be to make 2 wide platforms out of Wood Platforms, one above the other, and when the Wyvern appears, stand on the lower platform and just move left and right a little. Time your jump to the moment the head almost touches you. You should dodge its attacks most of the time.

Option 2
Make a sky bridge in the atmosphere (where gravity has less effect.) Use at least ~300 blocks so you can do a full run, jump, and float with Spectre Boots + Cloud in a Balloon twice. Build either Cobalt Repeater or Mythril Repeater, Cobalt Armor with magic buff and craft Crystal Storm. Then run fast so the Wyvern follows you in a more or less straight line, shooting him with Crystal Storm along his length until you're out of mana, then switch to the repeater (Recommended with Jester's Arrows) Once your mana is full again, switch back. If you reach the end of your bridge, turn around and run the other way. Using the atmosphere this way makes it easier to dodge the Wyvern's attacks. Another means of killing him easily is to have your Star Cannon, and around 10 - 20 fallen stars. Run so that he is following you, then shoot the stars through his body. With around 5 stars, I was able to halve his health. So depending on your accuracy, 10 - 20 stars should do it. The Minishark or Megashark also works in this situation. Make sure it has a higher-powered bullet, (Such as the Crystal Bullet which breaks into 3 seperate bullet causing additional damage.) Ironskin and Health regeneration potions are recommended and 400/400 health is ideal.

Option 3
With rocket boots, spectre boots, or wings, you can go in a repetitive motion of jumping and flying to the right, attack from above,and wait for him to come back into sight, then fly left, attack from above, and wait for him to come back into sight, and repeat this. By doing this he will continue to fly in this repetitive motion of back and forth, while you attack from above. I have also learned that using a Grenade works very well since all the segments of his body can take damage. A Grenade will be able to hit up to 6 segments of his body because of the explosion, but usually hits about 4. Still this method is extremely useful. The Flamethrower is also a good option, although this does not do damage to more than one section, if you fire it at 90 degrees to his body as he passes, a lot of damage will be done.

Option 4
Get a relatively powerful flail, (Sunfury, or if you're wanting top tier gear, a Dao of Pow ) Use a gravitation potion until it spawns, immediately use the gravity to your advantage and flip directly downwards (don't move, just make sure you're moving vertically constantly) the Wyvern will still catch up to you (recommended medium world or higher) and aim directly up with the flail when it gets near. With a Dao of Pow, you can take at least 1000+health off this creature per swing.

Option 5
Buy the Ice Rod, cast it under you while jumping up, (Works better with Rocket Boots and a Cloud in a Bottle, or other jumping items). Get the Wyvern's attention and jump back down, cast Demon Scythe going up, and keep casting it, and it will hit the Wyvern while you are falling down, then finish the battle on the ground level, Normally the Wyvern will have 1000/4000 HP left.

Option 6
Make a couple of gravitation potions, float to the very top of the world above your spawn. There will be a large amount of Harpies, but dodge their shots while taking them out with a ranged weapon of choice. Then, as the Wyvern appears, drop to the ground. The Wyvern will head directly towards you, slightly faster than you are. Use the Mini/Megashark to shoot straight down it, as it will hit every link. As it is about to hit you, move to the side and it will continue a ways and come back at you. Continue the fight by changing gravity to avoid it's attacks, and it shouldn't take long as the intial drop should have lowered it's health a lot. If need be, you should be close to your spawn to heal.

Option 7
You will need either a Magical Harp or a Demon Scythe, and some mana potions for this to work. Get to the top of the world with a gravitation potion and wait for Wyvern to spawn. as soon as he spawns, start killing him with your weapon, pausing only to heal/restore mana. Go up to the top of the world when you reach the ground, then back down when you reach the top, spreading the damage with your weapon until it dies.

Bugs

 * Sometimes, if a Wyvern is killed in multiplayer when it's laggy, it's head will stay and keep attacking you. This can get really annoying.

Tips

 * Since the damage the head does is much higher than the body, it's best to try and avoid it, even if it means having to touch its body.
 * It can follow you down to the ground.
 * Using the Dao of Pow can be extremely effective, however like any burrowing enemy, it cannot be confused.
 * Using Ranged weapons can be much more effective than melee. Good weapons would be the Starfury, the Starcannon, the Shotgun, any Repeater or the Megashark.
 * If you have a Demon Scythe, Water Bolt or Magical Harp, it may take very high damage if lined-up with projectiles trajectory.
 * You can also build a tall tower up from your spawn to aggro a Wyvern, then use the Magic Mirror to teleport down and hopefully have the Wyvern follow you. You can use a nurse at your house for this to make it even easier to win.
 * For first timers, it would be wise to go against this enemy in singleplayer to get used to its pattern.
 * There's a glitch where there can be more than 1 at a time.
 * If you die, they appear to automatically regenerate health back to 4000.
 * There is a rare glitch in which the Wyvern has a tail of the Bone Serpent
 * A Wyvern is able to follow you to your home as it can fly faster than you even if you're wearing Hermes Boots. Do not run away and go back to your home as it may catch you by suprise.
 * The Wyvern has a long body, which can be turned to your advantage by building a small room and using attacks that ricochet off walls (Cursed Flame, Crystal Storm, Light Disk...etc.) inside. As the Wyvern charges through, it will be hit by each projectile multiple times, increase your damage potential.
 * Using a spear, if available, is recommended do to a spear being able to strike in any degree angle of your character as well as damaging the wyvern multiple times in a single attack