Another old school Oriental Adventure conversion.
Jishin. The creature’s most dangerous weapon is its ability to create tremors in the earth. By striking its abdomen on the ground, the jishin mushi generates a small tremor, which grows in intensity with repeated blows. The effects of these tremors over successive rounds are as follows:
- Round 1: Any creature within 5 feet of the earthquake beetle must make a successful DC 17 Escape saving throw be knocked to the ground becoming prone.
- Round 2: Any creature within 10 feet must make a successful DC 17 Escape saving throw or be knocked to the ground becoming prone.
- Round 3: The radius of the tremors extends to 15 feet. Those within 5 feet of the creature are thrown violently about, suffering 26 (4d12) bludgeoning damage and losing the opportunity to make an attack that round.
- Round 4: The radius extends to 20 feet. Those within 10 feet suffer 26 (4d12) bludgeoning damage and lose the opportunity to attack.
- Round 5: The radius extends to 25 feet. Those within 15 feet suffer 26 (4d12) bludgeoning damage and lose the opportunity to attack. Cracks in the earth begin to appear within 5 feet of the creature.
- Round 6: The radius extends to 30 feet. Those within 20 feet suffer 26 (4d12) bludgeoning damage and lose the opportunity to attack. The area within 10 feet of the creature suffers the effects of an earthquake spell. At this point, the jishin mushi must take to the air to avoid the consequences of its own deeds.
- Round 7: The full effects of the earthquake spell manifest and persist for 1 minute.
Legendary Resistance (3/Day). If the earthquake beetle fails a saving throw, it can choose to succeed instead.
Magic Resistance. The earthquake beetle has advantage on saving throws against spells and other magical effects.
Reflective Carapace. Any time the earthquake beetle is targeted by a magic missile spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, the earthquake beetle is unaffected. On a 6, the earthquake beetle is unaffected, and the effect is reflected back at the caster as though it originated from the earthquake beetle, turning the caster into the target.
Siege Monster. The earthquake beetle deals double damage to objects and structures. This also applies to its jishin trait.
Ramming Legs. An earthquake beetle may use its reaction to attack any prone creature within 20 ft. of the earthquake beetle that stands up. Use the mandible attack action but instead of the target being grappled they are knocked prone again and lose their movement action on a failed Escape check.
Multiattack. The earthquake beetle uses Frightful Presence and then makes two mandible attacks.
Mandibles. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 33 (4d12 + 7) bludgeoning damage. If the target is a Huge or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the earthquake beetle can’t use its mandibles on another target.
Frightful Presence. Each non-insect creature that can see of the earthquake beetle within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the earthquake beetle is within line of sight, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the earthquake beetle’s Frightful Presence for the next 24 hours.
The earthquake beetle can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The earthquake beetle regains spent legendary actions at the start of its turn.
- Attack. The earthquake beetle makes one mandibles attack.
- Move. The earthquake beetle moves up to half its speed.
The jishin mushi is a giant carnivorous insect. Also known as the earthquake beetle, it is capable of generating tremors of extraordinary magnitude.
The jishin mushi has six legs and a plump body. A tough, bluegreen carapace covers its back, while thick gray plates protect its underside. Its legs are covered with black bristles and end in flat, bony hooks. These hooks are useless as weapons but helpful for digging.
The earthquake beetle’s carapace conceals a pair of wing sheaths. When it takes flight, the beetle raises the sheathes to expose four wings. The two smaller wings near the head help the creature maneuver. The two larger wings behind propel the insect through the air, beating so rapidly they nearly become invisible. When the beetle lands, it withdraws all four wings beneath the sheaths to keep them protected.
Two antlerlike feelers extend from the top of the creature’s head. Both are covered with tiny hairs. The feelers are the beetle’s primary sensory organs, providing a powerful sense of smell. With them, a jishin mushi can smell prey up to 100 yards distant.
A pair of bulbous black eyes sit atop the beetle’s head, and two strong mandibles curl out from its mouth. The jagged mandibles are well suited for crushing and tearing food, as well as for attacking enemies.
The jishin mushi is not aggressive by nature, attacking only to defend itself and to kill edible prey. Its powerful mandibles can inflict 33 (4d12 + 7) hit points of damage per bite. The mandibles also are used to grasp and drag victims back to the privacy of the forest. However, the mandibles are poorly designed to clamp objects, and most grasped victims easily can slip free. For this reason, the jishin mushi will ordinarily continue its attacks until its victim is dead or unconscious before dragging him off to eat.
The creature’s most dangerous weapon is its ability to create tremors in the earth. By striking its abdomen on the ground, the jishin mushi generates a small tremor, which grows in intensity with repeated blows.
Jishin mushi establish lairs in the deep woods, beneath piles of decaying vegetation, in crevasses, or — in especially large forests — in the trunks of rotting trees that have fallen to the ground. Occasionally, the beetles will burrow tunnels if the earth is soft enough. In any case, a jishin mushi’s lair is only temporary. The creature spends all waking hours prowling the forests in search of food. After a strenuous night of hunting, it rests in the nearest suitable lair.
A jishin mushi eats all types of meat. It is particularly fond of oxen and sometimes attacks these animals as they work in a farmer’s fields.
The ichor of the jishin mushi is greatly prized by incense makers, fetching as much as 20 sen for a flask. Certain primitive tribes consider larval jishin mushi a delicacy.