Deep Space

Deep Space is a biome that is 3 times huger than the normal space its located on the top of the normal space If you didnt defeated Moon Lord an dungeon guardian creature like will kill you

(Since you cant make the map huger in terraria dont think this idea will come true one day)

There is some minibiomes in

Nebula Comet

Mobs of their respective pillar will spawn

Vortex

Stardust Comet

Solar Comet

Prism Moon

Luminite meteor

BlackHole