Shrine of Sertrous
When the PCs arrive, read: You stand at the precipice of an enormous cavern that appears to have been blasted from the rock by primeval forces. The stone walls are rough and red, as if a scab had formed over a wound in the world itself. A mysterious black blot the size of an elder dragon stains the far wall. It radiates a pervasive cold, felt not on the skin but in the soul.
In the midst of that cavern, an enormous carved natural column resembles a winding serpent that rises up from the earth and goes back down again, twisting around itself until its head sits on the ground beside its tail. Though many of the sculpted details have been lost to time, it still looks real enough to come alive at any moment. The eyes of the idol, like the blot on the wall, radiate a frigid darkness.
Features of the Area
The area has the following features.
Illumination: The area boasts no natural illumination; the characters must provide their own. For each light source, roll 1d4. On a result of 1, it sheds only half as much light as normal; on a result of 4, twice as much. The light is unchanged on a 2 or 3. Reroll at random intervals (or each time you roll on the table, above). This effect occurs in both the passages and the various locations, including the shrine.
Rounded Floor: The rounded floor of the
passages adds 2 to the DC of Balance and Tumble checks. Any creature attempting to run or charge across this floor must succeed on a DC 10 Balance check or be unable to do so but it can act normally otherwise.
DC
Information Gained
15
The entity so honored is likely Sertrous, an elder evil that was once an obyrith demon, in the age before ages. The shrine has great power, which likely can be activated via some ritual at the idol.
25
As befits a shrine to a creature of primal chaos, the benefits are unpredictable -- and so are the costs for failure.
1-2
Failure; character is poisoned (1d6 Con/1d6 Con, DC 16 Fort negates).
5-6
Energy resistance 5 to a random energy type. Roll 1d4 upon first gaining this ability, and again upon awakening each day; a result of 1 indicates resistance to acid, 2 indicates cold, 3 indicates electricity, and 4 indicates fire.
9-10
Poison (Sp) 1/day.
The Shrine as a Magical Location
The power of Setrous, and the reverence of the Vanguard, have imbued the area with substantial magics that his followers can access -- but so too can certain PCs.
Lore: Characters can gain the following pieces of information about the shrine of Sertrous by making Knowledge (the planes) checks at the appropriate DCs, as given below.
Knowledge (the planes)
DC Information Gained
10 This area is clearly a shrine to some terrible reptilian power, possibly of the Abyss.
15 The entity so honored is likely Sertrous, an elder evil that was once an obyrith demon, in the age before ages. The shrine has great power, which likely can be activated via some ritual at the idol.
20 Activation of the shrine's power likely requires a show of devotion, such as placing one's hands in the eyes or mouth of the serpent.
25
As befits a shrine to a creature of primal chaos, the benefits are unpredictable -- and so are the costs for failure.
Prerequisite: Only chaotic or evil characters can access the power of the shrine. Other characters automatically fail (see below) when attempting to activate it.
Location Activation: Any character seeking the benefits of the shrine must strip himself of all magic items and place his hand -- without gloves, gauntlets, or any protection -- inside either an eye or the mouth of the serpent idol. The DM then rolls 1d12, due to the chaotic aspect of the shrine. Characters who are both chaotic and evil gain +1 on the roll. See Special Ability, below.
Any given character may attempt to activate the shrine of Sertrous only once per week, whether he succeeds or fails.
Recharge: The shrine of Sertrous can bestow its power on up to three different people before it's tapped out. Each "charge" recharges itself after 1d6+7 days.
Special Ability (Su unless stated otherwise): The recipient of the shrine's power takes on several aspects shared by Sertrous back when he was an obyrith, a primal demon predating the more familiar tanar'ri. With the exception of the "failure" result, these effects are cumulative. For instance, a character who rolls a 7 gains suggestion, energy resistance, and the bonus against mind-affecting effects and poisons.
A character currently possessed of powers granted by the shrine takes a -2 profane penalty on all Charisma-based skill checks except Intimidate, as the pseudoreal madness of the obyrith becomes faintly manifest in his eyes, his voice, and his mannerisms. Further, he radiates a mild chaotic and evil aura, in addition to whatever alignment auras he might normally possess.
The spell-like abilities have a caster level equal to the character's HD.
Roll Result
1-2
Failure; character is poisoned (1d6 Con/1d6 Con, DC 16 Fort negates).
3-4 +2 profane bonus on saves against mind-affecting effects and poisons.
5-6
Energy resistance 5 to a random energy type. Roll 1d4 upon first gaining this ability, and again upon awakening each day; a result of 1 indicates resistance to acid, 2 indicates cold, 3 indicates electricity, and 4 indicates fire.
7-8 Suggestion (Sp) 1/day.
9-10
Poison (Sp) 1/day.
11
Serpent's strike: Once per encounter, as a swift action, the character may adjust his stance, plus 11 mystically adjust the shape and flexibility of his limbs, to grant him an extra 5 feet of reach. This
effect lasts for 1 round.
Cloudkill (Sp) 1/day.
Sidebar: Upping the Ante
You may wish to consider granting these abilities to one or two of the yuan-ti inside Castle Serastis, under the assumption that they visited the shrine themselves in recent days. If the yuan-ti has only one or two of the powers, this shouldn't impact the CR; if the yuan-ti has most or all of them, consider increasing the CR by 1.
Duration: The spell-like abilities granted by the shrine remain for 1d4+4 days, regardless of how often they are used, and then disappear.
Aura: Strong conjuration and transmutation. Ability Value: 5,000 gp.