Note: This information was taken from TSR's original AD&D adventure, the Temple of Elemental Evil.
For the DM: Four hill giants dwell herein, members of the elite high guard of the Greater Temple. The room is simple and undecorated, about 25 feet tall and 60 feet long. All the furnishings are appropriately giant-sized. Two beds stand by each wall, north and south. The room is warmed and somewhat lit by a fireplace in the west wall, beside which are piles of small boulders. The wall itself shows signs of digging, and is greatly pitted. (The giants have worked this area for missiles.)

Under each bed is a large chest. Each chest contains clothing, food scraps, various mixed coins (about 1,500 gp worth in each, with 250 pound encumbrance), a few gems (1-10 per box, of random value), and souvenirs of past kills -- scalps, pelts, bones, and the like.

In actuality, only three of the giants are as they seem. The fourth is an imposter, actually being a half-elf spy. The hill giant Scorpp (who is currently living it up in area 318, unless slain by PCs) was replaced here by this character, one Kella by name. Scorpp is thus not missed in the least.

Kella is a druid, and possesses a valuable item made by her professional ancestors, a phylactery of change. This item enables here to use her innate shapechange ability to assume monster form as well as animal. The possible forms are still limited to monstrous reptile, bird, or mammal, the latter corresponding to the hill giant form. The phylactery does not radiate magic, and Kella carries no other magic items, to avoid exposure by detect magic or other means. Kella cannot cast spells in giant form, and will do nothing to give away her disguise; she speaks only when necessary, and is so immersed in her role that she has become almost giantish in her attitudes.

Kella has taken the form and jobs of old Scorpp, spying on the Greater Temple for the leaders of the Old Faith. She fears the current rise in evil power, and knows that time is limited. She also knows that she risks certain horrible death at the hands of luz himself should she be discovered, but things have gone well thus far -- nearly two months in all.

The half-elf can escape nearly any night if desired, but she awaits the arrival of some powerful group that might stand a chance at defeating the evil powers herein. If she notices the PCs sneaking about quietly, she will try to follow them and secretly reveal herself. If thus accepted, she will urge retreat so she can tell them critical things -- the numbers and types of monsters herein, the habits of the leaders, which corridors go where, and so forth. If she does not ally with the party beforehand, she will hold back in a large melee, watching to see if the party's resources and courage balance those of the evil horde. If it seems that her powers could swing the balance in favor of the attackers, she will change to her normal half-elven form and aid the party as best she can. If the party is too quickly defeated, she will wait for other challengers. If the party can defeat the evil ones unassisted, she will certainly not risk anything by revealing herself, instead shapechanging to some small avian form to make her escape.

Kella: AC 8, MV 9" or 12", Level 9 Druid, hp 45,
#AT 1, D by form, spell, or weapon, SA spells, SD spells
and phylactery of change, AL N; XP 3840
S 12 I 11 W 16 D 16 Co 13 Ch 15

Spells:

First level: detect magic (x2), entangle, faerie fire (x2), shillelagh, speak with animals
Second level: barkskin, charm person or mammal, cure light wounds, fire trap, obscurement, warp wood
Third level: cure disease, neutralize poison, protection from fire, water breathing
Fourth level: cure serious wounds, dispel magic, protection from lightning
Fifth level: wall of fire

Hill Giants (3): AC 4, MV 12", HD 8 + 2, hp 59, 41, 33,
#AT 1, D 2-16, SA boulders (D 2-16, normal ranges 6"/13"/20",
indoor ranges 3"/6"/12"); XP 2108, 1892, 1796 (1400 + 12/hp)