As large as a horse, the terrorantula is a twisted abomination of pallid chitin and black iron. It’s chassis resembles the phase spider it once was in general shape with bubbling lines of galvanic-charged goo framing the plates of its armor. The spider’s eyes have been replaced with one large oculus lens and its fangs with a pneumatic pair that inject some of its life-sustaining fluids directly into a victim. Its thorax is covered with thousands of rune-etched needles, each enchanted to disrupt a spellcaster’s mind.

Step 2 - Infiltration. “If I regret any of my recent actions, my darling, it is butchering the poor phase spiders I ensnared. There is some mote of intelligence behind their eight eyes, more so than the common child I would say. They did not understand the pain I inflicted upon them to make them better, to mold them to my glorious purpose. Yet, reborn as one of my terrorantulas, oh, they revel in their newfound power! Their ability to move between the ethereal and material plane proves quite useful in stalking and killing those fools of the Planar Guild. I even constructed bays within their hollowed thorax to house Sawfly Swarms. The real master stroke though is the pain pins I lined their backs with. Those damn magi won’t know what hit them and will fumble every feeble spell they attempt to cast.” -The Vespidae

Terrorantula

Unaligned

Armor Class 14 (natural armor)

Hit Points 136 (16d10 + 48)

Speed 30ft

Climb 30ft

Str 16 Dex 15 Con 17 Int 6 Wis 16 Cha 4

Damage Resistances lightning; bludgeoning, piercing, and slashing from nonmagical attacks that aren't adamantine

Damage Immunities poison

Condition Immunities exhaustion, frightened, petrified, poisoned

Senses darkvision 60 ft., tremorsense 10 ft., passive Perception 13

Languages understands Common and Draconic but cannot speak

Challenge 5 (1,800 XP)

Ethereal Jaunt.

As a bonus action, the construct can magically shift from the Material Plane to the Ethereal Plane, or vice versa.

Innate Spellcasting (3/Day).

The terrorantula can innately cast Fear (spell save DC 14), requiring no material components. Its innate spellcasting ability is Wisdom.

Sawfly Dispenser.

As a bonus action, the terrorantula may place a swarm of sawflies in any square within 5ft of itself or envelope a swarm of sawflies into itself. A swarm of sawflies within the construct has total cover.

The terrorantula may house up to 4 swarms of sawflies at a time. Any swarms of sawflies within the terrorantula when it is reduced to 0 hit points are automatically placed in any square within 5ft of the construct when it dies. Swarms of sawflies that cannot be placed in this manner are destroyed.

Spider Climb.

The terrorantula can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Actions

Bite.

Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 13 (2d8 + 4) piercing damage plus 4 (1d8) lightning damage.

Setae Spray (Recharge 6).

The terrorantula launches a 20ft cone of fine needles that are alchemically treated to irritate spellcasters. All creatures within the area of effect must succeed on a DC 13 Dexterity save or suffer 1d4 piercing damage.

Any creature with a spellcasting ability that takes damage from the spray must succeed on a DC 10 Constitution (Concentration) check to successfully cast a spell. If the creature is Concentrating on a spell, any Constitution (Concentration) checks it makes have disadvantage. This effect lasts until the pins are removed taking a creature's full action.