Dungeon of the Mad Mage: The altar of "we don't know"

 Having just slain the many-faced horror, the adventurers took their time to look around the cavernous hall. Unfortunately, we found nothing but broken mining equipment. Oh, and an altar.

So there's this altar in the room, clearly messed up by goblin hands. We had to avenues to investigate.

Selene tried to replicate the filthy, messy, sometimes bloody handprints on the altar, to no effect. She even cut her own hand to get some blood on, but nothing happened.

After a slip by the DM let us know it's a dwarven altar, I rectified our knowledge by doing a ritual of Comprehend Languages. I could then decipher the dwarven script, and read the prayers to Dumathoin. On impulse[1], I cleaned up the altar - by using Selene's fake magic cloak! 1500 gold for a cleaning rag is not a very good deal, but apparently the clean-up worked and I got an unspecified blessing. Hooray!

Selene then also tried cleaning here and there, but got nothing. Thanks for the cloak, anyway.

Next up, we backtracked to the electric laboratory to open up a door to a dead end we missed.[2] We encountered a couple of ghasts... 2 fireballs later, we were examining the headless skeleton in the room. I bagged it, along with the skull that was animated and flying around in the other room. Intact skeleton, maybe? Also, we found the final chapter of the necromancer's journal. She was seriously obsessed with lightning. Oh well.

We resumed the exploration of the caverns, this time encountering a pack of many limbed/faced/eyed creatures. The DM played his favorite "you are stuck in the tunnel and cannot get out because of the people in front of you" trick, so the combat encounter lasted a while, until the sorceresses managed to get in fireballing position. Selene got smart by flying out on her broom, but the creatures still got her with their blinding attack. Solid and I held the line shoulder to shoulder, and the creatures eventually died.

Pissed off at the surprise, I remembered the invisible owl familiar trick. My scout revealed sounds of battle coming from up front, so we rushed to save and/or loot the body of a fellow adventurer. Some human fighter, battling one eyed murlocs[3] and a many limbed fiend. 

We engaged the monsters, but the fiend cast Darkness. Szivem responded with a fireball, while Selene sent her driftglobe to dispell the darkness. We made short work of the now visible monsters, but the human had died in the conflagation. RIP. Time to loot!

[1] It's not the first altar that I encountered during our sessions.

[2] Thanks for the map!

[3] DM's description.