#Dungeon23 Tomb of the Vampire Queen, Level 8, Room 21

 Going back to Room 19 and then to the central passageway takes the party up to a room similar to Room 20.

Inside this wet room is what appears to be a gargantuan frog. Its evil eyes though, betray its true origins.

Dæmon, Hydrodæmon

Armor Class: 2 [17]
Hit Dice: 9+36**** (76 hp)
Attacks: 2 fore claws (1d8 x2), 2 hind claws (1d4), 1 bite (1d10)
Special: Spittle, spells, only harmed by silver weapons, immunity to acid and poison, magic resistance (35%), telepathy 100 ft.
THAC0: 11 [+8]
Movement: 30' (10')
  Swim: 240' (80')
Saving Throws: D8 W9 P10 B11 S12 SS 7 (9)
Morale: 10
Alignment: Neutral evil
XP: 3,607 (OSE) 2,300 (S&W) 3,800 (LL)
Number Appearing: 1d3 (1d6)
Treasure Type: I, Y

Hydrodæmon are frog-like daemons that swim the River Styx. They are the only known creatures in existence that can touch the waters of the Styx without suffering any ill effects.

Hydrodæmon are 10 feet tall and weight about 4,000 pounds. Large flaps of skin under their arms allow them to glide when leaping. The flesh of a hydrodæmon is warty and green. Its eyes are a sickly yellow in color.

Up to five times per day a hydrodæmon can expel a 20-foot long line of sputum that causes those hit to save vs. sleep (as the spell) for 6 rounds. Hydrodaemons can, at will, cast cause fear, darkness, detect magic, and dimension door. Once per day, they can summon an 8 HD water elemental.

They can communicate telepathically but have low intelligence. 

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This hydrodæmon is awkward on land, and there is not enough room for it to glide.  It has been trapped here since the necromancers controlled this place, and it is pissed off.