19th and last in the Divinities and Cults: Volume III series, we have Tiamat, Mesopotamian demon lord of abomination & monstrous tyranny.
1. How abominable can one get? The party will find out in the next encounter. Whether monsters, animals, people, or something else, each will have at least 1 mutation, granting them (roll 1d6):  a +2 bonus to certain rolls,  +1 HD,  the ability to make an extra attack for 1d6 damage each round,  as 1 and 2,  as 2 and 3,  as 1, 2, and 3. See Volume III for specifics on mutations. What is more, they will likely be especially vicious and insane (a base 75% chance).
2. Mutant! An NPC that the party knows turns out to have been corrupted by Tiamat. As a result, he or she is now abominable (as per encounter #1 above) and will also (roll 1d8):  try to kill the party at the earliest opportunity,  lure the party into a trap and then try to kill them,  as 1 or 2, but will also stop to eat his or her first victim too,  seek to spread his or her mutation to others via unnatural acts,  begin worship of Tiamat in earnest,  flee the area,  chop off the mutation, causing the loss of 1d4 x 25% hit points, reroll 1d6 twice.
3. Egads! A random, unlucky party member gains 1 mutation. As in encounters #1 and #2 above, he or she will become abominable and likely take some sort of dastardly action, though Chaotic party members are twice as likely to be selected as Lawful or Neutral ones for this result. Those of the latter alignments can also save vs. death to resist the urge to go mutant-crazy, but chopping off the altered part would still be a viable option.
4. An Everlasting Change that We Must All Believe In (or Else) occurs immediately before the party’s very eyes! Encounter #1, #2, or #3 above happens, but those witnessing it must also save vs. death or (roll 1d8):  think it’s just fine,  flee in terror for 2d4 rounds,  flee in fear for 1d3 rounds,  become nauseated (unable to act) for 1d4 rounds,  wet themselves, taking a -2 to all rolls until cleaned up,  pass out in shock for 4d4 rounds, [7-8] become morally outraged, gaining a +2 bonus to hit the mutant for the next 2d3 rounds. Lawful individuals gain a +1 bonus to this encounter roll, treating a result of 9 as 8 instead.
5. The corrupt salt waters of Tiamat flow into the area, causing her to birth two encounters in a most unnatural way- reroll twice on this table. In addition, all within 240’ who aren’t aquatic have their movement reduced by half until they leave the area, thanks to the presence of her waist-deep fluid and foul, floating miasma.
6. Doom! This area has been overrun by Tiamat’s progeny. Roll 1d8:  1d2 seven-headed hydras,  2d3 bull men,  3d3 lion men,  4d3 dog men,  5d4 scorpion men,  4d4 fish men,  a monstrous Kur!,  reroll twice. See Volume III for stats for these monsters.
7. A procession passes by, promoting ‘Variety, Love, and Acceptance’. Of course, these are Tiamat cultists who actually practice the exact opposite of what they preach, though if the party doesn’t have any faithful of Marduk amongst them, they only have a base 50% chance of attacking. The procession includes  1d4+1 Tiamat clerics,  1d3 +1 Tiamat priests,  1d3+1 Tiamat shamans,  1d2+1 Tiamat witches,  2d6+2 Tiamat cultists,  reroll twice. Each also has a base 33% chance of being abominable (hidden of course; otherwise see encounter #1 above).
8. Throwing off any veneer of civility, the faithful of Tiamat have begun to subjugate and destroy the local populace, causing genocide in the name of ‘Progress’. See encounter #7 above for the numbers of cultists involved, though each also has a 66% chance of now having a visible mutation/deformity with advantages as per encounter #1 to assist in their monstrous tyranny.
9. Not all give into Tiamat’s destruction so easily! A group of 2d4 Marduk followers (or similar local divinity) has assembled to espouse usurpation, storms, and protection of empire! They have knowledge of a Tiamat enclave 2d4 miles away, though they will happily slay any followers of that demon lord (or other mutants) they encounter along the way.
10. Tiamat’s words may be honeyed, but they never bring the paradise promised. Treat as #6 above, except roll twice to determine which offspring of Tiamat are now fighting each other. Wise party members would avoid the battle completely or else risk getting caught in-between such likely disputes between her children.
11. The Tablet of Destinies ordains that 1d4 class abilities be removed from an unlucky party member, whether it is a spell that can be cast, an ability achieved at level, or even a weapon that can be wielded. The only way to regain the use of these abilities is to slay a disciple of Tiamat, just as Marduk recovered the Tablet by slaying Kingu, the original unskilled laborer.
12. Some mistake Tiamat’s true nature. The truth is much worse: her tentacles can permeate through all manner of fell cults, creating a Multicult of sorts that works in tandem, at least until the humans have been destroyed! Roll again twice: once on this table and once on that of another fell entity that is currently allied with Tiamat, such as (roll 1d4):  Apep,  Dagon,  Set, or  Nergal. The party will then likely wish it was only a multi-headed dragon they had to deal with.
Sample 4th Level Cleric of TiamatAlign: C
Dmg: 1d6+1 (+1 club) and 1d6 (bird claw) or 1d6 (spear)
SP: Tiamat turn ability, mysteries, Hairy neck: CON bonus, Bird hand: extra attack (divine tests), -1 INT & WIS, 50% chance of being easily identified as a monster
1st level: (3+2) Create Water (saltwater), Cure Light Wounds, Entangle (x2, as tentacles), Charm Person*
2nd level: (2+1) BarkskinD, Scare*, Stinking Cloud*
Possessions: Scale mail, +1 club, spear, 38 gold pieces, scrolls to post advocating the superiority of hybrids.
Next week: we head north again to explore Clerics of Heimdall!
And upcoming work: The print versions of Volume I are ready (both for DCC RPG and Labyrinth Lord) and I’ll be ordering proofs to double-check them soon!