Homebrew Ankheg (humanoid) Species Details

They appear to look like odd mashes between Thri-kreen and giant multilegged ants.  They walk bipedal, and their legs are multisegmented.  They have 4 arms, and the lower arms are normal arms whereas the primary arms act like long half pincers.  jagged like claws.  Their secondary arms are three fingered and tend to be rather bulky, and they have longer bodies than other races, giving them surprising height of well over 6 feet to just over 7 feet.  Their heads have an odd crown like obtrusion, jutting out the back of their heads.  They have large ant like mandibles used for biting and cutting.  

They have a hard chitinous exoskeleton that gives them a relatively high natural armor but prevents them from donning anything greater than light armor, so this won't be a great build if you like to really deck yourself out.  They can however, use up to two weapons at a time.  They also like to use the hunting strategy of taking advantage of their burrowing speed to hide in the soil just below the surface, and when their tremorsense picks up on something they burst out and its dinner time folks.   Their multiple eyes (of which they have 4) give them great understanding of their surroundings.  

 

Ability Score increase

Your constitution increases by 2, and your strength increases by 1.

Tremorsense

When you are standing still and focusing, you can sense footsteps or vibration from up to 60 feet away accurately, allowing you to deduce the beings size, and exact location.  

Darkvision

C'mon we all know what Darkvision is here, we paly DND for crying out loud.  I don't need to write this.  (it's 60 feet sorry guys)

Many Eyed

You have proficiency in perception and investigation checks.

Bite

Your mandibles can make a bite with 1d10 + your proficiency bonus + your strength modifier of piercing damage.  You cannot bite and slash in the same turn, you can however, use one of each attack as you can make two natural attacks.  Once you make a bite attack though, you cannot do so until you have damaged any other being in a different way.  

Dig and Scuttle

Your primary blade arms can be used to dig through a malleable material such as dirt, sand, or any other material the DM says is available.  They can also be used as a weapon. They deal 1d8 + your proficiency bonus + your strength modifier of slashing damage and they have a reach of +5 feet.  You cannot grasp weapons or tools with these appendages, but the attack count as a bonus action.  You can attack with both arms at once.  

You also, as a bonus action, can drop and scuttle about on all of your legs like your ancestors, increasing your walking speed by 20 feet.  Every time you use this bonus action, the next time you use it the speed bonus decreases by 5 feet, and you regain all 20 feet after a short or long rest.  Also, while scuttling, you cannot use weapons other than your bite and primary digging arms.  

Natural Armor

Your exoskeleton gives you a base AC of 15 + your constitution modifier.  You cannot wear medium or heavy armor, but you can still gain the benefits of a shield.  

Multi Attack

You can attack with whatever weapon you hold, as well as any your natural attacks, but you cannot attack twice with weapons wielded by your secondary arms.

For example, say a Ankheg fighter has a shield in one arm, and a longsword in the other.  If it takes the attack action on enemy A for example, it can attack with its longsword and two slashing attacks, one from each pincer, or one pincer attack on bite attack.  It can still gain the benefit of the shield but can't wear more than its light chainmail.  If it uses its bite, it must now wait until it has successfully damaged enemy B before it can use bite again.  

Opportune Moment (pirates of the Caribbean reference there)

Starting at level 3, when you make an opportunity attack, instead of a normal attack you can go into Frenzy (you do not gain all of the benefits of the more advanced version below only those listed here) without expending the Frenzy bonus action, upon which time you can make 4 pincer attacks, and 2 bite attacks without needing to take the bite rest period, but you forfeit all weapon attacks with your secondary arms when you use this bonus action.

Once you have used this ability, you must complete a short of long rest before you can use it again.  

Burrow

Starting at 6th level, you can use this ability as your action, you burrow into the ground (unless material prevents this) and are concealed and considered stealthed.  An investigation or perception check with a DC of 20 can detect you, and while you are underground you have an AC of 10 + your normal AC.  If an unlucky person moves above you, and does not know you are there, you can burst out and make an opportunity attack, but you cannot make any bonus actions on that opportunity attack.  

Frenzy

Starting at 12th level, you can enter a barbaric mindless period where you more resemble your relatives than yourself.  You drop all weapons you are currently holding with your hands, you can make 3 consecutive turns, during which you can take the dash action as a bonus action, and you can make up to 6 pincer attacks per turn, or 3 bite attacks.  At the end of your frenzy, you can choose to use the burrow action.  wherever you want within 15 feet of your original position.  

Once you use this ability, you cannot use it again until you have either dropped to half of your health, singlehandedly killed a number of enemies equal to or greater than your proficiency bonus or completed 5 long rests or 15 undisturbed short rests.  

Ankheg (weaknesses)

Your swim speed is 0 because you sink like a freaking stone.  You are also incapable holding your breath for longer than 5 minutes other than by magical means.

You have a disadvantage against magic spells designed to charm or trick you.  

You have natural fear of cats.  Not like a big 'ol displacer beast, you're all good with those ones but the little house cats.  Kittens are worse.  Unexplainable but on sight you are automatically frightened and must use all of you turns to take the dash action and move away from them until you are at least 100 feet away.  You have a disadvantage against them when making saves against them, and you cannot attack them unless it is an opportunity attack.  (So, no Tabaxi on your team.) 

You are vulnerable to cold damage and experiencing cold damage drops all of your speeds by 50%.  

If you are knocked prone, your soft underbelly is exposed, changing you AC to 1 temporarily.  Your attacker also has an advantage for the damage roll, but they also have a disadvantage for the roll to hit as you 'flail about helplessly making it hard to strike.'  You can also get back up with only 5 feet of movement as you can roll over on to all of your legs.  

 

Ankheg (humanoid) Traits

Bursting from the dirt, showering the party with dust and grime, and massive, many legged monstrosity pulls itself from the ground to attack. This is the Ankheg, a mindless beast, uncapable of reason or understanding. Yet on rare occasion, one might find this horrifying creature standing by their side in even the darkest times.