"I am not versed in such matters, but do you think this liquid might have special qualities, restorative perhaps?"
As a cleric of the light, Gaven knows enough about Brother Camillus' association with healing to suspect that Oloc's proposed theory of restorative qualities is very possible.
Oloc takes some of the liquid in the cup of his hand. The liquid feels warm and clean. The mage applies it to the mysterious red substance to see if it can act as a solvent.
When the liquid touches the red pigment, Oloc hears a faint hiss escape the grim substance. It is not the hiss of alchemical reactions, but the all-too-emotional hiss of utter and bitter hatred. The clear liquid applied to the pigment rises from it in a wisp of vapor, and the pigment remains unaffected.
Gaven tries to lift the plate out of the alter and/or slide it to the side. The plate still refuses to budge.
Meanwhile, Duran continues to help search the area for a trigger for the trap door. The fighter notices that one of the sconces behind the altar shows evidence of a split between the stone of the sconce and that of the wall, very similar to the one in the shoulder of Brother Camillus' statue.
Duran gives the sconce a twist, and the small plate in the altar slides open with a delicate "snick" sound.
The now open panel reveals a compartment within the altar. The compartment is lined with unrusted steel. The steel shows evidence of severe burn marks. Inside the compartment is a steel handle, also bearing burn marks. In very small letters, engraved on the lining of the compartment are the words: