Arenas need space to move, cover that breaks line of sight and a clear view for spectators. An octagonal or round floor, a raised ring of balconies and a hazard (lava moat, pits) at the edge turn a flat box into a fight.
Generated by Cyrus from a written design. Previews show a cutaway: the roof and the two front walls are hidden so you can see inside.
A 58 x 28 x 58 round boss arena: a lava moat, two bridges, a raised central platform and a pillar ring.
Main blocks: blackstone, basalt, polished blackstone bricks, cracked polished blackstone bricks, gilded blackstone
Larger than 48 blocks: load the .nbt with /place template, not a structure block.
A 48 x 20 x 48 octagonal arena: a central fighting floor, a lava moat with two bridges, cover pillars and spectator balconies.
Main blocks: stone bricks, cracked stone bricks, polished blackstone bricks, lava, polished andesite
One arena room up to 64 x 32 x 64. Game logic (rounds, teams, kits, scoreboards) is a plugin: the Cyrus mod builder makes those.
A WorldEdit schematic (.schem, Sponge schematic version 3, for WorldEdit 7.3+ and FAWE) and a vanilla structure file (.nbt, for structure blocks and /place template). Both are made from the same build, block for block.
Yes, within the limits above: describe it in the build generator (for example "a round PvP arena with a lava moat, cover pillars and a spectator balcony") or paste a picture.
