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The Forgotten Smugglers' Cave: Index of Posts

An index of posts describing the Forgotten Smugglers' Cave, an adventure for Holmes Basic characters levels 2-4.                    ...

Friday, March 17, 2023

Rock Crab (New Monster)


Rock Crab by Lore Suto

The Rock Crab, a new monster, originally appeared only in the Random Encounter table of the Forgotten Smugglers' Cave adventure (indexed here). However, inspired by Lore Suto's fantastic illustration for them, I recently realized that if they also climb walls they fill a dungeon niche similar to piercers (which aren't in the Holmes Basic Monster List, so would essentially be a new monster themselves for a Holmes adventure), so I have revised the adventure to replace the piercers in Area 9 and the Random Encounter table with rock crabs.

Rock Crab

Least Large Huge Giant
Move 120 feet/turn,
90 feet/turn
90 feet/turn,
60 feet/turn
60 feet/turn,
30 feet/turn
30 feet/turn,
15 feet/turn
Hit Dice 1 hp 1/2 1 2
Armor Class 7 5 3 1
Treasure Type nil nil nil nil
2 claws for
1 hp each
2 claws for
1d4 each
2 claws for
1d6 each, or
1 drop for 1d8
2 claws for
1d8 each, or
1 drop for 1d12

These cavern-dwelling crabs have shells resembling cave formations, and thus can camouflage themselves in their environs by tucking their legs and claws underneath and remaining motionless. In this manner they attempt to surprise their prey as it passes (1-3 in 6). 

Furthermore, as they grow, the spikes on the back of their shells grow taller, coming to resemble groups of short stalagmites or stalactites. The huge and giant crabs have claws strong enough to grip rock, and will often climb to the ceiling and attempt to drop on their prey (surprise on 1-5 in 6; if the crab gains surprise, the drop is treated as an attack roll with a +4 to hit and doing the indicated damage; if a character is not surprised, they can automatically avoid the dropping crab). 

The least rock crabs will generally be found in hatcheries in large numbers (4d6). As they grow, they wander to other caverns but often stay in loosely associated groups (2d4 large, 1d6 huge, or 1d3 giant rock crabs). After one crab makes an initial attack, it will drum its claws on the floor for one melee round to alert the others in the area to join in. During this round it will attempt to dodge attacks but will not make an attack.
While the rock crab lives on land, they can still swim slowly and will sometimes dwell on the ceilings of water-filled caverns inhabited by fish upon which they can prey.

Their shells are extremely tough and can be fashioned into shields that are equal to metal in strength.


  1. I like this. The progression from 1hp monster up to 2HD is a good scale. How big are these creatures?

    1. Thanks, Jacob. Perhaps these sizes on average: least (1 hp): 1/4 foot diameter shell; large (1/2 HD): 1 foot diameter; huge (1 HD): 2 foot diameter; giant (2 HD): 3 foot diameter. This is going off the Giant Crab in the Monster Manual, which is 3 HD and 4+ foot in diameter.