Clark Ashton Smith somehow failed to make it into Appendix N of the original Dungeon Master’s Guide, Gygax’s list of inspirational and educational reading.
This stands out when you read a few passages from The Seven Geases (1934):
The Lord Ralibar Vooz, high magistrate of Commoriom and third cousin to King Homquat, had gone forth with six-and-twenty of his most valorous retainers… He and his followers were well armed and accoutered. Some of the men bore coils of rope and grappling hooks to be employed in the escalade of the steeper crags. Some carried heavy crossbows; and many were equipped with long-handled and saber-bladed bills which, from experience, had proved the most effective weapons in close-range fighting with the Voormis. The whole party was variously studded with auxiliary knives, throwing-darts, two-handed simitars, maces, bodkins and saw-toothed axes. The men were all clad in jerkins and hose of dinosaur-leather, and were shod with brazen-spiked buskins. Ralibar Vooz himself wore a light suiting of copper chain-mail, which, flexible as cloth, in no wise impeded his movements. In addition he carried a buckler of mammoth-hide with a long bronze spike in its center that could be used as a thrusting-sword; and, being a man of huge stature and strength, his shoulders and baldric were hung with a whole arsenal of weaponries.
[...]
Most of the caves were narrow and darksome, thus putting at a grave disadvantage the hunters who entered them; and the Voormis would fight redoubtably in defense of their young and their females, who dwelt in the inner recesses; and the females were fiercer and more pernicious, if possible, than the males.
By the way, geas is the Scottish spelling of an old Gealic word for a magical obligation — and it is not pronounced like geese, but more like gesh:
In Irish mythology and folklore, a geis is an idiosyncratic taboo, whether of obligation or prohibition, similar to being under a vow or spell.
The geis is often a key device in hero tales, such as that of Cúchulainn in Irish mythology. Traditionally, the doom of heroes comes about due to their violation of their geis, either by accident, or by having multiple geasa and then being placed in a position where they have no option but to violate one geis in order to maintain another. For instance, Cúchulainn has a geis to never eat dog meat, and he is also bound by a geis to eat any food offered to him by a woman. When a hag offers him dog meat, he has no way to emerge from the situation unscathed; this leads to his death.
(Hat tip to The Mule Abides.)