Marble Cave

A long horizontal tube in the Cavern layer, floor to ceiling in marble, studded with spikes of stone and lined with pots you will not see anywhere else. Cave systems crossing it chew the shape up, so the neat corridor in your head is often broken into chambers with ordinary rock between them. Some caves come with a cabin built from Smooth Marble holding a Marble Chest, and that chest is nothing special: it rolls the same loot as any other underground chest.

Mini biomes skip the normal spawn requirements, and this one is unusually loose. A single Marble Block in range is enough for Hoplites and Medusa to appear, either inside your immediate spawn radius or in a band roughly 30 to 60 tiles out. More blocks raise the rate, but one is sufficient, and Marble Walls count for nothing at all.

Two things follow from that. First, the danger leaks. You can be in a perfectly ordinary stone cave with a seam of marble poking through one wall and still get a Medusa. Second, standing on marble yourself boosts the rate so hard that nothing else is needed, which is the whole design of a Medusa farm: lay a platform of marble, stand on it, wait.

Hoplites throw javelins on a downward arc that outranges most pre-Hardmode weapons and hurts a great deal when it connects. They are a normal problem, fought from behind cover like any other ranged enemy.

Medusa is why people give marble a wide berth in Hardmode. She raises her arms, and if you are still in her line of sight when the wind-up ends you get Stoned: locked in place, unable to act, and taking heavily inflated fall damage if you happened to be in the air. Several seconds is a long time to be a statue in front of everything else in the cave.

The counter is geometry rather than defense. One block between the two of you cancels the whole thing, so fighting her from around a corner or through a one tile gap makes her close to harmless. Never engage while falling, and never engage over a pit.

Hoplites drop the Gladiator Helmet, Breastplate and Leggings along with the Javelin, which is a genuinely usable early throwing weapon rather than a novelty. Medusa drops the Medusa Head, a magic weapon that turns her own trick back on whatever is in front of you and holds up well past the point you got it.

The marble itself is one of the better building materials in the game and feeds a full furniture set, and the pots and cabins are worth breaking on the way through.

Two approaches work. Tunnel in from above and fight downward so there is always a ceiling to duck behind, or let the terrain do it for you. A cave that generated deep enough often floods with lava, which deletes Hoplites and Medusas on contact. Pouring lava into the gaps between the stone spikes yourself turns the corridor into a safe walk, provided you are honest about how easy it is to step in your own trap.

The pots, the columns and the enemies are all a Greek and Roman joke, which is also a rough guide to what you should expect to be thrown at you.

Two seeds change things. Drunk worlds swap the generation shapes of marble and granite, and in a Constant world marble reaches the surface, though the Greek enemies stay where they belong.