Plantera

Plantera is a Hardmode Boss that can be fought after The Destroyer, Skeletron Prime, and The Twins have been defeated.

Summoning
After all mechanical bosses have been defeated, one or more Plantera's Bulbs will appear somewhere in the Underground Jungle. Destroying one of these bulbs requires a Pickaxe or a Drill, and upon doing so, Plantera will spawn.

First stage
Plantera chases the player around the jungle, using its hooks to grapple surfaces. It fires thorns and occasionally spits bouncing spiky balls.

Second stage
Once Plantera is brought down to half its original health it will change to its second form, with its pink bud falling away to reveal a thorn-filled mouth. It retains its previous attacks but moves quicker and more erratically, as well as sprouting a number of tentacle mouths that stretch outward on thin strands (similar to the Wall of Flesh's "Hungry" minions, though the tentacles do not detach when damaged). It will also release floating pink spores that drift toward the player (similar to the spores released by the Giant Fungi Bulb).

Enraged stage
Plantera only becomes "enraged" if it follows the player out of the Underground Jungle, for instance to the surface. This causes it to gain significantly more damage and movement speed, and will attempt to remain directly on top of the player, causing constant damage. It still must "grapple" walls with its vines in order to move, so having a tall enough arena would still allow a player to fight it on the surface.

Aftermath
When Plantera is defeated for the first time it will always drop a Grenade Launcher with Rocket I's for ammo, as well as the Temple Key. The Pygmy Staff and the Seedling also have a chance to drop. From the second time onward the drops become randomized, although it will always drop a Temple Key each time it is killed.

The Temple Key will allow access to the Lihzahrd Temple, and, through crafting, the Dungeon Keys which can open the Dungeon Chests, giving access to more near-endgame weapons.

Defeating Plantera causes new enemy types to spawn in the Dungeon who drop new weapons and items. Through crafting of these items it can offer further access to the previously inaccessible Pumpkin Moon and Frost Moon events.

Also, after Plantera is defeated, some NPCs will sell previously unobtainable items: For example, the Truffle will now sell the Autohammer which allows converting Chlorophyte bars into Shroomite bars. The Cyborg NPC will appear too, provided a vacant House is available.

Tips

 * Excavate a sizeable area to allow easier dodging before summoning Plantera.
 * Plantera's Bulb can spawn in player-made Jungle Biomes, which can provide a slightly easier way to fight Plantera.
 * Line up 2 teleporters ~50 blocks away from each other in two small separate rooms with a tiny hole. When Plantera is summoned, fire at it using a Megashark or Clockwork Assault Rifle. When it gets too close, teleport to the other room.
 * To find Plantera's Bulbs more easily, press M (for the map). Zoom in and look for a pink/purple rectangle. Put your mouse over the rectangle and it should say Plantera's Bulb.
 * Narrow Passages slow Plantera as it takes more time for it to grip the surrounding terrain. Use of the Death Sickle in the narrow passages will result in up to 3,000 max damage in a 30-40 tile tunnel.
 * If you have already beaten the Golem, the Stynger is very effective against Plantera.

Trivia

 * The name "Plantera" is a word play of the American thrash metal band Pantera, which is Redigit's girlfriend's favorite band.
 * Plantera drops "The Axe", which looks similar to the Washburn and Dean electric guitars often used by late Pantera guitarist Dimebag Darrell.
 * Plantera's boss music features heavy electric guitar use.
 * This boss bears a resemblance to Kalle Demos from The Legend Of Zelda: The Wind Waker.
 * It is likely that the reason Plantera attacks you after destroying a bulb is because the bulbs look like a little like a baby Plantera.(Note: birds usually behave like this, attacking whoever killed their baby.)

History

 * When killed for the first time the message is now "Screams are echoing from the dungeon..."