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Cyberphrenic Tadpole

A tiny segmented terror, a mechanical mix of insect and crustacean yet trailing filamentous strands almost like a jellyfish, skitters and crawls while thrashing its many limbs and whirring menacingly. Its narrow body is covered by thin protective plates while its underside is a mass of pinprick diodes and backlit wiring.

Diminutive construct, neutral

Armor Class 14
Hit Points 10 (3d4+3)
Speed 10 ft., climb 10 ft.

17 (+3) 16 (+3) 14 (+2) 13 (+1) 15 (+2) 4 (-3)

Skills Athletics +0
Damage Immunities poison, psychic
Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned
Senses darkvision 60 ft., passive Perception 10
Challenge 1/2 (100 XP)

Special Traits

Internalization. A cyberphrenic tadpole that begins its turn grappling can make a grapple check to burrow inside its host rather than simply maintaining its grapple. If the grapple check succeeds, the cyberphrenic tadpole implants itself along the host’s brain stem or spine, entwining its filaments into the target’s neural fibers. While internalized, the cyberphrenic tadpole has total cover against any attacks coming from outside the host’s body; however, if the target takes 10 or more points of lightning damage in a single round, the cyberphrenic tadpole is incapacitated for 1d10 x 10 minutes.

Removing an internalized cyberphrenic tadpole is difficult, though as long as it remains helpless it can be extracted using normal chirurgery, requiring 1 hour of work and DC 14 Dexterity (thieves’ tools) and Wisdom (Medicine) checks.

Removing the cyberphrenic tadpole causes a creature to permanently 1 lower one ability score by 1 (roll 1d6 to randomly determine which) unless the result of the check is 18 or higher (in which case no permanent damage is done).

If the cyberphrenic tadpole is not rendered inert first it can be removed with emergency surgery, though it squirms and slithers through its host’s innards to avoid removal.

Performing emergency surgery requires an action, bonus action, movement, and reaction that provokes opportunity attacks and can be performed only on a willing or incapacitated host. The host takes 1d4 points damage per round and is poisoned for 1 hour per round of surgery undertaken.

Even after the surgery is complete, the host takes 1 point of Constitution bleed. Each round of emergency surgery, the creature trying to remove the cyberphrenic tadpole makes a Dexterity (thieves’ tools) and Wisdom (Medicine) check with an initial DC of 15, but each time a check is failed both DCs increase by 1. After making 1d4 successful checks, the cyberphrenic tadpole is isolated and a single ally of the surgeon can attack the cyberphrenic tadpole with a ready action. The cyberphrenic tadpole has three-quarters cover (+5 bonus to AC and Dexterity saving throws) against this attack, and a missed attack strikes the host instead. If the cyberphrenic tadpole is destroyed, it can be removed as if it were inert (see above).

Alternatively, the surgeon can attempt to tear the cyberphrenic tadpole free with an opposed Strength (Athletics) check. This traumatic removal from the host’s nervous system deals 3d6 damage and permanently reduces all of the host’s ability scores by 1, but also leaves the cyberphrenic tadpole stunned for 1d4 rounds (after which it attempts to attach itself to the nearest living creature).

If the attack fails to destroy the cyberphrenic tadpole or the grappling fails to dislodge it, the cyberphrenic tadpole slips away and 1d4 additional successful Dexterity (thieves’ tools) and Wisdom (Medicine) checks are required to make another attempt to remove it. Only one attack or attempt to grapple is allowed, though allies may use the Help action or otherwise assist the attacker or the surgeon in their attempt.

Telepathic Relay. A cyberphrenic tadpole emits a telepathic homing impulse that connects it with its creator and its host. Its creator can sense the cyberphrenic tadpole’s (and the host’s) location once between long rests as if using the locate creature spell.

In addition, once between long rests the creator can spend 1 minute attuning their mind to the cyberphernic tadpole in order to transmit one of the following effects to the host: detect thoughts, dream, modify memory, phantasmal killer, sending, or suggestion. These spell save DCs are based on the creator’s proficiency bonus and the cyberphrenic tadpole’s Wisdom score. Because of the creator’s attunement with the host’s mental processes through the cyberphrenic tadpole’s neural grafting, the host has disadvantage on saving throws against effects used by the creator that would cause the charmed or frightened condition.


  • Attach. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d4+4) piercing damage, and the cyberphenic tadpole attaches to the target, its barbed filaments boring into the target in search of solid attachment points and anchoring it in place. The cyberphrenic tadpole gains the grappled condition (moving to the squares its target moves to) but its target does not. Its AC becomes 10 as it begins burrowing into the target’s flesh at the start of each of the cyberphrenic tadpole’s turns, causing the target to take 4 (1d8) piercing damage as it bores a hole through which to invade its host. The cyberphrenic tadpole has advantage on Strength (Athletics) checks to maintain its grapple on a foe once it is attached. An attached tadpole can be struck with a weapon or removed by grappling. The cyberphrenic tadpole can detach itself by spending 5 feet of its movement.

Cyberphrenic tadpoles are created by mad scientists to implant into their victims, rendering them more pliable to later mental influence and control and allowing the scientist to monitor the host’s activities. A host may be unaware that a cyberphrenic tadpole has been introduced, as they may be implanted while a victim is unconscious, unaware, or otherwise helpless and the wound left behind by its entry into the host healed and memory of this invasion of the flesh erased by a concomitant invasion of the mind. Grafting itself onto the host’s nervous system, a cyberphrenic tadpole is very difficult to remove and subsists parasitically on the bioelectrical and biothermal processes within the host’s body.

A cyberphrenic tadpole’s body is usually only a few inches long and an inch wide, though its tentacular filaments can be up to a foot long. The creature as a whole weighs only a few ounces.

Crafting a Cyberphrenic Tadpole. A mad scientist may craft a number of these constructs equal to half their proficiency bonus, replacing 2 prototype drones for every cyberphrenic tadpole they posses.

Section 15: Copyright Notice

Mutants and Mad Scientists (5E) © 2018, Legendary Games; Authors: Jason Nelson, Mike Myler, and Clinton J. Boomer.