The Caves

The Caves is Act 1's Chapter 3 area, unlocked after completing The Sewers. This dark cave complex inside a mountain is covered in water, webbing, and abandoned mining infrastructure, with its soundtrack "Crystalline Dreams" lending an eerie atmosphere to the spider-infested depths. The Caves serve as a major branching point in the game's progression: completing it opens both the hard path through The Alley (leading to The Junkyard) and access to the Wall of Flesh, which connects to the secret Throbbing Domain.

Water tiles persist from The Sewers, so electric attacks remain highly effective. Webbing throughout the caves adds a spider-themed layer of hazards. The enemy roster features Skull Oozes, Brain Drains, Bats, Spider Cats, Spiderlings, Toadies, and the dangerous Ten Tickles, which attacks adjacent water tiles and can teleport through connected water. Albino Tom Toms and Korbee appear as tougher variants. The Big Slime serves as the area's mini-boss.

The chapter boss is Spinnerette (250 HP, 300 in Champion mode), a massive spider that begins with a fake-out fight against "One Baby Spider" before revealing herself. Spinnerette's Large Bite is a devastating 2x1 strike that destroys the target's body if it downs them, eliminating any chance of revival. She lobs webs and spiders in cross patterns, generates Spiderlings when damaged (which inflict Infested status), and can retreat to the ceiling for a turn of invulnerability. Attacking her from behind triggers an Enraged state that trades ceiling access for increased damage and speed. Fire-based attacks counter web effects, and knockback helps manage Spiderling swarms. On-kill effects benefit enormously from the constant spider spawning, enabling combos like Soul Reap plus Brainstorm for infinite mana loops via Spiderling farming.

At the end of The Caves lies the Wall of Flesh, a key progression gate. Inserting the Throbbing Gristle weapon (obtained from defeating Guillotina 1) opens the path to the Throbbing Domain. Alternatively, a cat can bite the wall using its Constitution stat to gain mutations, food, or birth defects. Defeating Spinnerette grants class-specific Active Abilities, such as Metronome for Collarless, Paw Breaker for Fighter, and Ball of Spiders for Hunter. Exclusive loot includes Twine gear (grapple chance, flammable), Rock equipment (high shield, brittle), Miner items (accuracy plus poison immunity), Gemstone pieces (kinetic spikes), and the Golden Pickaxe weapon.