Just a friendly guide that will make you a terraria pro and let you beat any boss (almost any)

Items got in this guide will be most recommended and BEFORE defeating the boss.

King Slime I would say is the easiest boss. His movements and teleporting makes him so easy that you can beat him even with a copper broadsword. So how to kill him you ask. Well i usually get some iron/lead armor and mostly a water bolt from dungeon but if youre not lucky enough for a waterbolt maybe just get a starfury from floating island. Not lucky still? make flaming arrows with an iron bow/lead bow/gold bow/platinum bow. Easy! Or just get some platinum/gold armor with platinum/gold bow and flaming arrows. Or even shurikens and grenades are not too bad. In expert mode, King slimes has 2,800 HP and if you hit him he summons Spiked Slimes.

Similar to king slime its movement is easy to dodge. Eye Of Cthulhu has 2 phases. 1 As an eye and 1 as a mouth. If you take half of cthulhu's health it will become the mouth. So how to kill it? Same with king slime, yeah easy right? You can use the mount from king slime too if youre lucky. In expert mode Eye Of Cthulhu in the second phase charges into the player. It also has 3640 health in expert mode.

Eater Of Worlds is most effectivly defeated using grenades, shurikens or jester's arrows. What about armor you ask? Same as king slime and eye of cthulhu. In expert mode the Eater Of Worlds shoots some kind of Vile Spit at the player. In expert mode the eater of worlds has an astonishing 10479 health!!! more than the wall of flesh in normal mode!

Brain of cthulhu can be defeated with the same armor as before BUT to kill it you have to kill the floating eyes before the brain of cthulhu becomes vulnerable. Recommended is a weapon that pierces (like the jester's arrows again or a spear). In expert mode in the second phase 3 mirror images of the boss appear. The lower the health the more visible they are. Brain of cthulhu also has 1700 health in expert mode.