Good luck without an arena, its almost impossible. even with an arena its very difficult.
Sadly, I'm unable to post a screenshot of the arena my friend and I build but I'll try to describe it:
Try to use everytrap you got from the Lizard Temple.
We started to make a big area completely flat, then we put a small "chamber" in the middle containing a campfire (for healthregen boost). On both sides of the chamber with the campfire we've put lava. Not much, about 3 to 5 pixels deep. So monsters will burn, but the loot wont get destroyed. At the sides the lavapool we've put a chain of dart traps, connected with lots of pressure plates and 1 sec timers. Also a birds spawner with a lever to activate the pressure plates. It causes 1 continuous chain of arrows.
We made a "bowl" above the lavapool, connected with the "campfire chamber" we put a bridge above it. Just in range of the campfire AOE, but high enough so that big mobs will fit below the bridge. On the sides of the bridge we put honeybaths of 3 blocks long and 1 block deep. And also a heartlantern on both sides to stack the healthregen buff. Also on the sides below the bridge we put spikeball traps which fall in the bowl below the bridge for even more damage.
And finally above the bridge we've put spear traps. Just high enough so the player won't get hit.
Hopefully this is helpfull enough, I'll look if I can post a screenshot later today.
- a small box for you to stand in with honey and a slime statue.
- campfire and heart lanterns
- any buff potion you can get your hands on
- full damage boosting menacing accessories
- best reforge on all weapons
- spear traps underneath you hooked to alternating timers
- teleporters moving enemies directly under the spear traps
- an arena in the sky so that all the enemy spawns will happen in your arena to maximise kill speeds
You can, if you want. There is one easy "arena". Basically you need
- tons of cannonballs
- building material
- heart lanterns
- one Dungeon spike
All you do is make a small box, at the top of the box, Place your cannon, preferably on a platform.
Have the box have two layers of platforms. one right under the other. Have an opening at the bottom of the box so that the enemies get hit by constant cannon fire.
place the Dungeon spike under the platform so you take constant damage. Don't worry that is what the Heart lantern and campfire are for. Make a small hole so the mobs can enter. The mourning woods won't be able to climb to you so you should be safe.
Make sure the trap isn't near any caves. Now all you need to do now is summon the pumpkin moon. Place yourself on the spike and constantly spam cannonballs facing upwards.