Guys im having a lot of trouble and i need this to beat the bosses!
what boss is that?
You know what? I'll try my best here to guess the boss
1. Eye of Cthulu - just build a quick arena area with what ever and some wood platfroms and use whatever projectiles you got. Make sure it's got some decent space so you can run when it hit's it's second form
2. Eater of Worlds - he is stupid easy either try and up your mp via stars and use a vilethorn on it or if you have a flail weapon like the ball of hurt use that.
2.5. Brain of Cthulu - again not a hard boss a bit harder then it's corruption counter part do to it's dissapearing, reappearing act and that it's harder to get to spawn on the surface. if you got say The Undertaker from one of the hearts stock up on ammo or if you have the funds for it you can buy a mini-shark from the gunsmith and use that while keeping a good distance away, if you want you can try and clear out some of the crimson blocks to open up a wider area to battle the brain in, if you don't have a pick that can break those types of blocks yet you can either go with sticky bombs(gel+bomb) or stock up on purification powder from the dryad and purify the blocks and then mine them out.
Just keep a good distance with range weapons or spells and take out it's eye minons first then just pound away at it in it's second form just make sure you got a chance to move when it comes at your or if your going melee then make sure your far enough not to get hit but still close enough to land a hit. He's pretty simiple.
3. Skeletron - mini shark and/or thorn chakram(6 jungle spores and 15 stingers) and if needed a blade of grass(a sword forged with materials from the jungle) since both the thorn chakram and the blade of grass can inflict poision it can make easy work of Skeletron. The main thing is try to take out it's head, you can take out it's arms and hands which can make the fight easier but to kill it you must take the head out. So use your own judgement.
4. Queen Bee - she's easy just wait till she stops to try and fire bees at you and swing or blast away and then jump over her when she flys towards you. Seriously she just either trys to ram you or stops and fires bees. Pretty simiple fight.
5. Wall of Flesh - First off don't try to flee this fight and especially don't magic mirror out.. you will be sorry if you do. So make sure your magic mirror is out of your hotbar so you don't use it by accident.
Now before summoning him make sure you have some strong melee weapons I recomend having one flail either a Blue moon or a Sunfury as well as Night's Edge(1 fiery greatsword, 1 muramasa, 1 blade of grass, 1 lights bane or 1 blood butcher combined at a demon/crimson altar, just open your crafting window at said alter with all 4 swords) , a strong magic attack if you found a flamelash use that if not then use the strongest magic you got, a minishark with tons of bullets and a strong bow and the best arrows you can craft.
Now once you have your gear ready and you should have a full set of hellstone armor, if not go make that and if needed craft some obsidian skin potions, water walking potions and water breathing potions on top of your health potions. Also make sure you have a ton of non-crimson/corruption blocks handy, now take those blocks and build a long bridge across hell and if you accidently killed a voodoo demon and the guide doll drops into the lava before finishing quickly use your obsidian skin and water walking potions and just fight also keep in mind what side the doll dropped as that will show you where the wall will spawn from as it starts from the very end of one side or another.
If you get your bridge make sure you have a large enough gap over the lava to drop the voodoo doll into, now run while taking the tenticles out first melee works well on them either night's edge or a strong flail, once the tenticles are off switch to your minishark and aim for the eyes and the mouth as those are his only vunerable parts once the tenticles are gone, when you run out of bullets switch to your bow, run of arrows then switch to magic and alternate between it and your flail or flamerang if you have one when your MP runs out and once it regenerates then switch back to it, ect. the key thing is to keep a good distance between you and the wall if it get's close enough it will grab you and chew on you for quite a bit of damage
Harmode bosses.. your on your own for those.. I only ever beaten The Destroyer.