Before the hex-priests bound the empire to the Maralith Queens, the land of Pra-Kryush had its own pantheon of local deities. With the rise of the Queens their worship was suppressed, the priests broken or sacrificed, and the temples demolished. Today, little remains of their faith and even the oldest amongst the tiefling elders remembers naught but odd references. Nevertheless, the Old Gods are not dead. Without mortal worshippers to sustain them they are so faded now as to be little more than wandering wisps. Most are like dotards with fading memories of their former glory, some even forgetting their own names. Some still cling to an abandoned shrine, idol, stele, cenote, or other lonely site in the jungle. In that locale, referred to as a shrine manse, they have some small power left.
Outside of these shrine manses, there are still many remnants about, such as building stones scavenged from their razed temples with some carvings left undefiled. Here and there are troves of holy items stashed by faithful priests to keep them from destruction by the minions of the Queens. A few of the greatest and oldest temples were so steeped in holiness that no corrupted being could enter, and so they were sealed by the demon-minions and forsaken.
The names of the Old Gods are long-forgotten, even to the gods themselves, for they have gone senile. A person contacting one will experience strange visions appropriate to the deity's domains. If the person tries to resist the visions, they must make a WILL save (DC 25) against each of the deity's three domains. If they embrace the visions, or fail a WILL save against any, they will gain a "Weirding" (containing a boon and a curse) for each.
When each manse is contacted, the GM will secretly make three random rolls on the domain list for the forgotten deity's three domains. The player of an affected character will then roll 1d6 (1-2/3-4/5-6) to see which of the three affects them. The GM will note which weirding the character gains and reveal the effects when appropriate.
There are twelve domains on the list. To keep things fun for the players, I'll just reveal one domain "weirding" as an example:
Wierding: you can speak with wild animals (boon); but domesticated animals panic near you (curse)