Into the Tethydid’s Gullet
Today, I take a break from my AD&D Deities & Demigods-to-5E conversions because I got distracted by the critter in the video above. If you’ve not seen this critter in action, check it out, and then read on to meet it statted out for three versions of D&D.
The tethydida is a monstrous marine predator that inhabits warm, tropical waters near reefs. It has a green, semi-transparent hide of thick, spongy tissue encasing thousands of gallons of viscous slime in which float various organelles. The tethydid is voracious and aggressive. It reaches lengths of 30 feet.
For B/X D&D:
Armor Class: 6
Hit Dice: 9*
Move: 30′ (10′), Swimming: 60′ (20′)
Attacks: 1 bite
Damage: 3-18
No. Appearing: 1-2 (1-4)
Save As: Fighter: 5
Morale: 10
Treasure Type: Nil
Alignment: Neutral
The tethydida attacks by expanding its bulbous head and biting at everything in a 10-foot radius. Make a “to hit” roll against all targets in the area of effect. If a “to hit” roll for the bite is 4 or more than the number required (or a 20, in any case), creatures of man-size or smaller will be swallowed whole and absorbed by a digestive organelle, taking 3-12 (3d4) points of damage each round thereafter.
For AD&D:
Frequency: Rare
No. Appearing: 1-4
Armor Class: 6
Move: 3″//6″
Hit Dice: 9
% in Lair: Nil
Treasure Type: Nil
No. of Attacks: 1
Damage/Attack: 3-18
Special Attacks: Swallow whole
Special Defenses: Nil
Magic Resistance: Standard
Intelligence: Animal
Alignment: Neutral
Size: L (30′ long)
Psionic Ability: Nil
Attack/Defense Modes: Nil
Level/XP Value: VII/1,300 + 12/hp
The tethydid attacks by biting. Its bite affects a 10-foot radius. Any hit 20% over the required score (that is 4 or more over the required number) or a 100% (die roll of 20) score in any case indicates the tethydid has engulfed its victim. A mature tethydid can swallow, whole, a creature as large as 6′ or so tall and up to 4′ wide, or vice versa. Any creature swallowed whole is absorbed by a digestive organelle and will be dead in 6 melee rounds. The tethydid will digest its meal in 12 turns, and that time the victim is totally gone and cannot be raised from the dead. Note, however, that a creature swallowed can try to cut its way out of the tethydid. The inner armor class of the tethydid is 9, but each round the creature is in the tethydid, subtract 1 from the damage each attack against the tethydid’s interior. This subtraction is cumulative (-2 on the second round, -3 on the third round, et cetera).
For 5E:
Huge beast, unaligned
Armor Class 14 (natural armor)
Hit Points 85 (9d12+27)
Speed 10 ft., swim 20 ft.
Ability Scores STR 22 (+6), DEX 9 (-1), CON 17 (+3), INT 2 (-4), WIS 11 (+0), CHA 5 (-3)
Saving Throws CON +6, WIS +3
Senses darkvision 60 ft., passive Perception 10
Languages —
Challenge 5 (1,800 XP)
Hold Breath. While out of water, the tethydid can hold its breath for 1 hour.
Water Breathing. The tethydid can breathe only underwater.
Actions
Massive Bite. The tethydid targets a point it can see within 10 feet. Each target within 10 feet of that point must make a DC 15 Dexterity saving throw, taking 16 (3d6+6) piercing damage on a failed save, or half as much on a successful one. If the target that fails its saving throw is a Medium or smaller creature, the target is also swallowed by the tethydid. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the tethydid, and it takes 15 (6d4) acid damage at the start of the tethydid’s turn.
If the tethydid takes 18 damage or more on a single turn from a creature inside it, the tethydid must succeed on a DC 16 saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the tethydid. If the tethydid dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 10 feet of movement, exiting prone.
