Gargantuan Crab, Steamed (CR 10)

This 40-foot crab is bright red and smells delicious.

gargantuan undead, neutral evil

AC 17 (chitinous carapace)

HP:

Body: 145 (10d20 + 60)

Right claw: 33 (2d20 + 12)

Left claw:  17 (1d20 + 6)

Speed 40 ft

Str 21 (+5), Dex 9 (-1), Con 22 (+6)

Int 10 (+0), Wis 7 (-2), Cha 1 (-5)

CR 10 (5,900 XP)

In lair: CR 12 (8,400 XP)

Immune fire

TRAITS

Meaty Claws. The crab's claws have separate hit points, and can be attacked separately from the body. If a claw dies is reduced to 0 hit points, that claw is killed. If the body is reduced to 0 hit points, the crab is killed.

Amphibious, Spider Climb, etc.

ACTIONS

Multiattack: The crab makes as many claw attacks as it has claws, then a bite attack against one creature in its claws.

Trample: The crab makes a leg attack against each creature in reach (maximum 8 targets).

Claw: +9 to hit, reach 10 ft, one target. Hit: 27 (4d10+5) bludgeoning damage. A Medium or smaller creature is grappled (escape DC 19). Each claw can only grapple one target at a time. Target is dropped if claw is killed. (Into the boiling water, if the crab is in its lair.)

Bite: +9 to hit, reach 0, one creature grappled by the crab. Hit: 21 (3d10+5) slashing damage.

Leg: +5 to hit, reach 5 ft, one creature. Hit: 16 (2d10+5) piercing damage.

The Crab's Lair

The crab lives in a naturally boiling lake in the middle of the tundra, spanned by a narrow bridge. It mostly stays underwater, but springs out when prey are near.

ENVIRONMENT FEATURES

Steam. The steamy air rising from the lake is pleasantly warm compared to the icy tundra for miles in every direction.

Boiling water. Any creature submerged in the lake takes 14 (4d6) fire damage at the start of each of its turns.

Bridge. The bridge has no convenient means of climbing back up if you've fallen off. Better lower a rope or something.

LAIR ACTIONS 

The crab magically causes one of the following effects each round at Initiative 20. It can't use the same one twice in a row.

Wave of water. A wave of boiling water strikes a 10-foot length of the bridge. Each creature in the area must make a DC 13 Strength saving throw. Success: 3 (1d6) fire damage. Failure: fall into the boiling lake.

Water level rises. Boiling water rises knee-high for the rest of the round. Everyone take 7 (2d6) damage at the end of your next turn if you're standing on the bridge.

Inspired by a misreading of a classic module, this bastard has become a legend in our game group. To bring him back for 5e, I've beefed up the stat block to play more like a real boss fight, not just a sack of hit points with basic attacks.