The hardest for me are the Twins, they are just too hard, I have trouble dodging Spazmitism's breath.
One good tip for many bosses if you are not-so-skilled at dodging, is.... if you can't dodge it, then soak it.
Now, you're not going to soak the green fire breath no matter what; it does way too much damage. However... Spaz has to slow down to use it and it has a relatively short range. The simple and easy way to counter that, is with a long tiered platform arena.
I would make a platform arena that is about 300-500 blocks wide, and make it two stories, each story being about I don't know, perhaps 20-30 blocks high, and use Leaf-tier wings (Leaf, Frost, or Flame) along with Specter or better Boots. Yes, use the wings AND boots; the boots will give you run speed and will make you ascend faster when you jump/fly, and will also prolong your flight time.
And of course, wear tank armor. You could go with Titanium, but I would actually recommend Adamantite Melee Armor.
If you can kill Destroyer, you can make a Megashark which is an excellent choice for fighting the twins, yes even while wearing Tank armor. If you have Crimson, I would recommend using Ichor Bullets. You could use Crystal Bullets instead or even Cursed Bullets, I've used all three of these options before and they all work reasonably well.
The rest of your accessories don't really matter as much; you could opt for a Ranged Damage Emblem, or perhaps try to get a Cross Necklace (which would help loads with the other eye's laser fire).
But basically the strategy is to just keep running away. Whenever Spaz decides to start breathing, you'll already be in the process of running away from him and he should pretty much never hit you with it. And of course, you want to place Heart Lanterns and Campfires all over the arena to have the buffs up full-time.
it was so hard to beat at first when 1.2 came out for PS3 but a cupple years latter i notices i was using turtle armor with a perona gun, what was i thinking, but i knew i was bound to be a ranger when i saw what i was doingPlantera
every time you want to summon him. Early on when you don't have souls to spare it can be very hard to practice the fight.
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