Big Bugs! I’ll skip the obvious Sir Mix-A-Lot joke, but I do like these underutilized monstrous insects. They can pop out of the ground to nab unsuspecting PCs and then crush them in their acid-dripping mandibles. Good times!

They have an uncommon weakness in their soft bellies, expressed by having a lower AC when prone. Hint at that and then your players can try to flip them over for easier stabbing. It’s a nice touch that can make them a little more engaging than your standard AC/HP/damage bag of stats.

Ankhegs slotted pretty well into my ongoing CR bump experiment. A CR 1 bug is a handy thing to have around, and a CR 4 bug is a bit frightening. Their damage output is decent, especially if they get someone caught in their grip. I gave them a harder carapace and kept their HP under control. This encourages the aforementioned flipping over and keeps them from sticking around too long. Do some damage and die, that’s what I like my monsters to do. Invoke the adrenal dynamic of fear and relief!

Ankheg, Lesser

Large monstrosity, unaligned

Armor Class 14 (natural armor), 11 while prone

Hit Points 26 (4d10 + 4)

Speed 30 ft., burrow 10 ft.

STR DEX CON INT WIS CHA

15 (+2) 11 (+0) 13 (+1) 1 (-5) 13 (+1) 6 (-2)

Senses darkvision 60 ft., tremorsense 60 ft., passive Perception 11

Languages —

Challenge 2 (450 XP)

Actions

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) slashing damage plus 3 (1d6) acid damage. If the target is a Large or smaller creature, it is grappled (escape DC 12). Until this grapple ends, the ankheg can bite only the grappled creature and has advantage on attack rolls to do so.

Acid Spray (Recharge 6). The ankheg spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must make a DC 13 Dexterity saving throw, taking 7 (2d6) acid damage on a failed save, or half as much damage on a successful one.

Ankheg, Greater

Large monstrosity, unaligned

Armor Class 17 (natural armor), 12 while prone

Hit Points 85 (10d10 + 30)

Speed 30 ft., burrow 10 ft.

STR DEX CON INT WIS CHA

18 (+4) 11 (+0) 16 (+3) 1 (-5) 13 (+1) 6 (-2)

Senses darkvision 60 ft., tremorsense 60 ft., passive Perception 11

Languages —

Challenge 4 (1,100 XP)

Actions

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 14 (3d6 + 4) slashing damage plus 7 (2d6) acid damage. If the target is a Large or smaller creature, it is grappled (escape DC 14). Until this grapple ends, the ankheg can bite only the grappled creature and has advantage on attack rolls to do so.

Acid Spray (Recharge 6). The ankheg spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must make a DC 14 Dexterity saving throw, taking 14 (4d6) acid damage on a failed save, or half as much damage on a successful one.