Giant Shelly

Giant Shellies share a slot with the Crawdad and the Salamander. Every world picks two of those three and locks the third out for good, and a world running both crawdads and salamanders will never produce a shelly. The game accounts for it: filling in the two your world does have unlocks the missing bestiary entry as well, and any two banners from the trio can be turned into the third.

It shuffles around the cavern at walking pace until it decides to attack, then tucks into its shell, spins up and hurls itself at you. While it is rolling it takes less damage and the contact hit is heavy for the depth you meet it at. The move runs on a fixed script: about a second curling up, a short spin, a slide until it hits something solid, then a moment to unroll. Landing any damage on it at any point cancels the whole thing.

The wait between spins is not fixed. Up close it charges rarely, and every hit you land resets that wait from the start. Back off past about a dozen tiles with a clear view of it and the charges come several times as often. From properly far away it barely stops at all. That inverts the usual advice, since standing near a shelly and hitting it quickly is safer than shooting it from across the cavern, and any fast firing weapon can lock it out of the attack permanently.

• The charge is aimed the instant it curls up, using wherever you were standing at that moment. Step aside and it commits to empty air, though it does keep track of you afterwards and will try to slam down once it gets overhead.
• Finishing a spin in water sends it straight into another one, so a cavern pool makes the fight considerably worse.
• They cannot drop through platforms. A few long platform rows through the tunnel or farm you are working in cuts the charges down to almost nothing.