Xenomorph, Facehugger (5e Creature)
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Tiny monstrosity, unaligned
Acid Blood. Any nonmagical weapon made of metal or wood that hits the facehugger corrodes. After dealing damage, the weapon a permanent and cumulative -1 penalty to damage rolls. If it drops to -5 the weapons is destroyed. The a attack on the facehugger does damage to it but also to the host dealing twice as much damage to the host
Grappler. If an attack from the facehugger hits the target, the target is grappled and cannot escape as the facehugger's tail wraps around the target's neck. The target creature can resist the grapple each round of combat by making a DC 13 Strength saving throw. Upon failure the facehugger latches unto the target's face and begins the impregnation.
Impregnation. The target is rendered unconscious, the DM then rolls a 4d6, after the rolled amount of hours have passed, if the Facehugger hasn't been removed, the Facehugger falls off and dies and the target is diseased. In the period before giving birth, the target creature starts to feel sick, its speed is halved and has disadvantage on attack rolls and saving throws. At birth, the Xenomorph Chestburster chews its way out of the target's chest in one round, killing the target in the process. A chestburster can be removed with a lesser restoration or greater magic to cure a disease.
Spider Climb. The facehugger can climb difficult surfaces, without the need to make an ability check.
Tackle. Ranged Weapon Attack: +2 to hit, reach 10/20 ft., one creature. Hit: 2 (1d4) bludgeoning damage.