Here is a mutated variant of the classic pack-hunting dromaeosaurid, ready-made for the rules-light post-apocalyptic settings of Cepheus Atom.
The Rad-Stalker (Mutated Deinonychus)
The Rad-Stalker is a terrifying twist on pre-collapse cloning experiments gone wrong, further warped by centuries of background radiation. They are larger than their ancestors, measuring roughly 4 meters long, completely hairless/featherless, and covered in mottled, leathery skin that bleeds toxic bile when ruptured.
Instead of simple feathers, their forelimbs have mutated into jagged, chitinous scythes, and their classic sickle claws are jagged and prone to delivering nasty infections.
Cepheus Atom Stat Block
STA: 8
DEX: 9
END: 10
Lifeblood: 18
Melee: 7
Stealth: 6
Speed: 14m
Armor: 1 (Thick, calloused hide)
Weapons: Sickle Claw (1d6+2 damage) or Scythe Arms (1d6 damage)
Special Abilities & Mutations
Pack Tactics: If more than one Rad-Stalker is attacking the same target, they gain a +1 bonus to their Melee rolls.
Irradiated Bite / Claw: Anyone wounded by a Rad-Stalker must make an END task check (Difficulty: Average) or contract radiation sickness, taking 1 point of STA damage per hour until treated or dead.
Pounce: If the Rad-Stalker moves at least 6 meters directly toward a target before attacking, its first attack knocks the target prone unless they succeed on an END or DEX check.
Encounters & Behavior
Rad-Stalkers hunt in small family units of 3 to 6 individuals. They are hyper-intelligent for beasts, capable of setting simple ambushes in ruins or rocky canyon passes. They actively track targets by scent and the faint hum of electronics, which seems to irritate them.
Here is a d6 table for harvesting a Rad-Stalker carcass. Survivalists can use these parts for crafting, barter, or uncovering lost pre-collapse tech.
Rad-Stalker Harvest & Loot Table
| d6 | Harvested Item / Loot | Value (Credits / Barter) | Rules Effect / Use |
| 1 | Intact Sickle Claw | 50 Cr | Can be fashioned into a heavy combat knife or short sword (Melee, 1d6 damage). Grants a +1 bonus to intimidation checks if visibly worn. |
| 2 | Irradiated Bile Gland | 100 Cr | Contains enough toxic fluid to coat up to 3 melee weapons or pieces of ammunition. Successive hits inflict 1d6 residual radiation damage on the next round. Must be harvested with a successful DEX check or the harvester takes 1 point of STA damage. |
| 3 | Leathery, Calloused Hide | 150 Cr | Can be treated by a skilled armorer to craft custom light armor (Armor: 1, grants +1 to Stealth checks in rocky or desert wasteland terrain). |
| 4 | Swallowed Pre-Collapse Tech: Battery | 200 Cr | Found deep in the gizzard. A still-functional, high-capacity fusion cell or battery unit. Can completely power an energy weapon, a heavy flashlight, or a vehicle's auxiliary system. |
| 5 | Swallowed Pre-Collapse Tech: Data-Chit | Variable | A cracked but readable memory drive from an old research lab. A hacker or tech-merchant can extract the data to reveal the map coordinates to an unlooted bunker or a hidden cache of medical supplies. |
| 6 | Mutated Adrenal Gland | 300 Cr | If chemically stabilized, it can be refined into 2 doses of "Slingshot" (a combat drug). Consuming a dose grants +2 to DEX and +4m to Speed for 1d6 combat rounds, followed by a -2 penalty to all actions for an hour due to severe fatigue. |
Harvesting Note: Harvesting a carcass safely requires roughly 10 minutes and a knife. If a player rolls a natural 2 on their check (critical failure), they accidentally puncture a radiation pocket and immediately contract radiation sickness (1 point of STA damage per hour until treated).
Here are three adventure hooks featuring Rad-Stalkers to drop into your Cepheus Atom campaign:
1. The Hum in the Walls
The Setup: The outpost of Rust-Hope recently repaired an old pre-collapse power generator, bringing electricity back to their perimeter fences. However, the high-frequency hum has driven a nearby pack of Rad-Stalkers into a frenzy.
The Twist: The creatures aren't just attacking; they are actively digging underneath the settlement to destroy the generator. The players are hired to hunt the pack in their subterranean den before they breach the outpost's floorboards and cut the power entirely.
2. Blood in the Water
The Setup: A vital oasis town has been cut off from its trade routes. A massive, heavily mutated alpha Rad-Stalker—known to locals as "Old Scythe-Tail"—and its pack have claimed the only local watering hole as their nesting ground.
The Twist: The pack isn't there by accident. A rival faction or a rogue wasteland bandit group is deliberately feeding the Rad-Stalkers contaminated meat near the oasis to drive the townspeople out, planning to claim the water source for themselves once the settlement collapses.
3. The Prodigal Pup
The Setup: A frantic settlement leader offers the players a massive reward to wipe out a pack of Rad-Stalkers that has been picking off their livestock and night watchmen.
The Twist: The pack is aggressive because the leader’s own reckless son stole a live Rad-Stalker hatchling, hoping to train it as a weapon or sell it to a fighting pit. The mother and her pack are tracking the hatchling’s scent, and they won't stop tearing the town apart until they get it back. The players must decide whether to return the pup, fight the furious pack, or deal with the greedy locals.
