Ankheg 5e: The Burrowing Ambush, the Grab and the Acid Line

An ankheg is a CR 2 Large Monstrosity with AC 14, 39 hit points (45 in 2024), a 10-foot burrow speed and 60-foot tremorsense. It waits under the soil, comes up under someone, and bites for 13 damage while grappling them (escape DC 13); after that it bites the same creature with Advantage. Its recharge attack, Acid Spray, is a 30-foot line of acid. The 2024 ankheg sprays harder (14 damage, DC 12) and can spray while it's holding someone, which the 2014 version can't.

Table of Contents

• •Ankheg Stat Block (2014)
• •The Ankheg in the 2024 Rules
• •How Ankhegs Fight
• •Running an Ankheg Encounter
• •How Players Beat Ankhegs
• •Ankheg Encounter Ideas
• •Frequently Asked Questions

Ankheg Stat Block (2014)

The ankheg from SRD 5.1:

Read the AC line closely: 14, or 11 while prone. Knocking an ankheg over is worth three points of AC on top of the Advantage melee attackers get against a prone target.

The bite has a built-in restriction. Once the ankheg grapples a creature, it can bite only that creature until the grapple ends, and it can't use Acid Spray while it has anyone grappled. A 2014 ankheg that grabs the fighter is locked onto the fighter. With Intelligence 1, that is how it should play: it grabs whatever is closest and doesn't let go.

The Ankheg in the 2024 Rules

SRD 5.2.1 keeps CR 2 (450 XP), AC 14, the speeds, the senses and the bite damage.

Net effect: the 2024 ankheg is tougher and more flexible. It can hold the fighter in its mandibles and spit acid down the line of people running to help. Its save DC dropped by 1, but the damage went up by a third. The prone-AC weakness is gone, so shoving it over is now only worth Advantage.

How Ankhegs Fight

The ambush. An ankheg burrows at 10 feet per round, too slow to chase anyone underground. It waits instead. Tremorsense tells it the exact position of anything touching the ground within 60 feet, so it lies a few feet under a field, a road or a cave floor until something walks over it, then rises and bites.

How surprise plays out:

• •2014: the DM decides who notices the threat. Nothing about a buried ankheg is visible unless someone spots disturbed earth, so a party that isn't checking the ground is surprised and loses its first turn.
• •2024: surprised characters roll Initiative with Disadvantage. The ankheg's Initiative is only +0, so Disadvantage just evens the odds against characters with a +2 or +3 bonus. Whenever its turn comes, it attacks from underneath, and the party has someone in its jaws before it has seen the ankheg.

The grab. The bite is +5. Against AC 16 that hits on 11 or higher, 50%. A hit deals 13.5 on average (10 slashing + 3 acid) and grapples a Large or smaller target. Every bite after that has Advantage, 75% against AC 16. A grappled character escapes with an action and a DC 13 Strength (Athletics) or Dexterity (Acrobatics) check. A fighter with Athletics +5 makes it 65% of the time, and every failed attempt is a turn spent not attacking.

A character grabbed on the first bite takes about 34 damage over three rounds (13.5, then two bites at 75%), which kills most level 3 characters. The rest of the party has to choose between rescuing and killing.

The acid line. Acid Spray is a 30-foot line, 5 feet wide. Party members on a narrow road, in a tunnel or walking in single file through crops are the target.

The ankheg starts the fight with it available. In 2014, the best sequence is to spray first, while it holds no one, then bite. If it needs the spray later, it can release its victim (no action required) and spit. The 2024 ankheg just bites first and sprays whenever the recharge comes up.

Retreat. An ankheg at low hit points burrows straight down. At 10 feet a round that doesn't take it far, so a party with a readied attack can finish it. Burrowing works through sand, earth, mud and ice. Both editions' rules say a burrower can't go through solid rock without a trait that allows it; the 2024 ankheg has one (Tunneler, 5 feet per round), and the 2014 ankheg has none.

Running an Ankheg Encounter

An ankheg is 450 XP. With the 2024 XP budget per character (SRD 5.2.1), for four characters:

Under the 2014 Dungeon Master's Guide guidelines (used by our encounter calculator), two ankhegs are 900 XP × 1.5 = 1,350 adjusted XP: Hard for four level 3 characters (Hard starts at 900, Deadly at 1,600).

Two ankhegs in one field play very differently from one. Each grabs a character, and the rest of the party splits to help. For a first fight against them, use one ankheg at level 2 and give the party a clue before it strikes: a dead cow half dissolved by acid, or a farmer's warning about holes in the barley.

How Players Beat Ankhegs

• •Don't walk in a line. Spread out more than 5 feet sideways and Acid Spray catches one person at a time.
• •Get off the ground. Tremorsense only detects creatures in contact with the same ground and can't detect flying creatures. A character on a flying mount or under a levitation effect isn't on its radar.
• •Shove it over (2014 especially). A Medium character can shove a Large creature. A prone 2014 ankheg has AC 11, and melee attacks against it have Advantage: a +5 attacker goes from 60% to hit to about 94%.
• •Kill it rather than wrestling free. Escaping costs a full action at 65% or worse. At 39 or 45 hit points, two or three characters focusing it for one round often end the grapple permanently. Shatter (3d8 thunder, Con save, ankheg Con +1 or +2) or a Guiding Bolt on the ankheg helps the next attacker.
• •Fight on stone against a 2014 ankheg. It has no trait for burrowing through solid rock, so a rocky outcrop is a safe place to stand and a place it can't escape into.
• •Watch the Intelligence. It has Int 1 and doesn't recognize traps. Bait (a goat on a rope, a rhythmic pounding on the ground) draws it where the party wants it.

Ankheg Encounter Ideas

Before the harvest. A landowner's barley is ready to cut, and three field hands have gone missing in a week. He refuses to let the party dig or burn the crop. They have to find the ankheg in waist-high grain, which lightly obscures everything, while it tracks their every step through the soil.

The single-file road. A trade road runs between two irrigation ditches on raised earth. Wagons travel it in a line. An ankheg has learned that the road vibrates when wagons come, and it waits under the third bend. Its Acid Spray runs straight down the line of wagons and drivers.

The new tunnel (2024). Miners hear something grinding through the rock behind the east wall, getting closer every shift. A 2024 ankheg is tunneling into the mine with Tunneler. The party has time to prepare an ambush of their own, and the tunnel it leaves leads back to a nest of two more.

Frequently Asked Questions

What CR is an ankheg in 5e?

An ankheg is CR 2 and worth 450 XP in both the 2014 and 2024 rules. It has AC 14 and 39 hit points (45 in the 2024 rules).

How does an ankheg's Acid Spray work?

It spits acid in a 30-foot line, 5 feet wide, and recharges on a 6. In 2014 it's a DC 13 Dexterity save for 10 (3d6) acid damage, half on a success, and the ankheg can't use it while it has a creature grappled. In 2024 it's DC 12 for 14 (4d6), and it can use it while grappling.

Can an ankheg burrow through rock?

The 2014 ankheg has no trait that lets it. The 2024 ankheg has Tunneler: it burrows through solid rock at half its burrow speed (5 feet per round) and leaves a 10-foot-diameter tunnel behind it.

How do you escape an ankheg's grapple?

Use an action to make a DC 13 Strength (Athletics) or Dexterity (Acrobatics) check. The grapple also ends if the ankheg dies. While it lasts, the ankheg's bites against the grabbed creature have Advantage.

Why is an ankheg's AC 11 while prone?

The 2014 stat block gives it a weak underside: AC 14 normally, 11 while prone. Knocking it over also gives melee attackers Advantage. The 2024 ankheg drops the reduced prone AC.

Stat blocks: System Reference Document 5.1 (2014) and 5.2.1 (2024), Wizards of the Coast, CC-BY-4.0. Tactics, encounter math and ideas are Loreify's own.