Took a look how to model some tropes in Mythras. Here is one you know well – go see the movie if you have not seen it.
Deep within the subterranean caves of Monster Island or half-buried in the shadows of the Field of Dead Glass, explorers sometimes stumble upon what appear to be leathery, ash-grey urns or oversized, petrified melons. These are Ash-Cysts, a horrific, dormant parasitic life-form mutated by the apocalyptic Firefall that destroyed the ancient Artmali Empire. Sometimes these are guarded with Warding Runes just beyond the edge of the reach of the Cyst,
Standing about three feet tall or bigger specimens bit taller, the cyst has a thick, rubbery, translucent exterior. A bright light shone behind it reveals a sickening, venous structure and something dark and curled pulsating within. At the apex of the leathery ovoid is a fleshy, cross-shaped fissure sealed shut by a layer of dried, caustic resin.
When a warm-blooded creature approaches, the cyst reacts. With a wet, peeling sound, the four “petals” at the top fold back, revealing a glowing, fleshy interior before a terrifying, pale, multi-jointed horror resembling a metamorphosis of spider, scorpion and a crab violently erupts outward.
Armor: 4-point leathery hide (Pod); 1-point pale flesh (Stomach-Parasite)
It is incredibly fast, lighting quick reflexes, faster than most humans. After the initial leap if that fails, it needs to wait a bit to gather the leaping energy again or it may only scramble towards the nearest living creature and climb up it towards its head.
Thermoception (Life Sense) The pod has no eyes. Instead, it possesses the Perceptive trait attuned to heat. It can sense the body heat of mammalian or reptilian prey approaching within 10 meters, triggering the pod to open.
Trapper The cyst is an ambush predator. This ability represents a one-shot trap attack. When the victim steps within range, the cyst launches its stomach-parasite. Because this is a sudden, springing trap attack from an immobile object, the target must use the Evade skill rather than Parry to avoid being struck.
Grappler If the Trapper attack connects, the pale, multi-fingered stomach wraps around the victim’s head. It automatically establishes a grapple, blinding the victim. The target must win an opposed Brawn roll against the parasite’s Brawn to pry the horrific, tightening grip off their face.
Asphyxiation & Implantation (Blood Drain): Once gripped, the parasite forces a proboscis down the victim’s throat. The victim begins to suffocate, and at the start of each Combat Round, they lose one level of Fatigue. If the victim is rendered unconscious, the parasite successfully implants a chaotic embryo in their chest before detaching and dying.
Acidic Blood: This is the ultimate defense mechanism, making companions hesitate to help. The creature’s internal fluids are highly pressurized and caustic. If a party member attacks the parasite while it is attached to their friend’s face, any damage that penetrates the parasite’s 1-point armor causes Acidic Blood to spray out. This inflicts 1d3 acid damage for 1d3 rounds to both the attacker and the grappled victim. The acid eats through worn armor before affecting flesh, easily ruining helmets and weapons.
If the party fails to carefully pry the parasite off (perhaps by using the Sunder special effect with surgical precision, or applying intense fire to its body to force a retreat), the victim is implanted.
The victim will wake up hours later feeling fine, but with a ravenous hunger. Within 1d4 days, “Exploding Fever” takes hold. If powerful healing magic or a complex Healing skill surgery is not performed, the victim’s chest violently erupts, birthing a highly aggressive, subterranean horror—perhaps a mutant Chaos Hybrid—that instantly scurries into the dark to grow
Inspired by Xenomorphs in the movies.
You can find the Ash-Cyst at meg
Other creatures to encounter – just look at the MeG page or the MeG Library page
Notes From Pavis 