Songs of Erui: Encounter Features

I didnt want to write about this because it relies on a lot on the stuff I've thought of for The Hydra's Grave, and I'm concerned that some of my players might read it. The Hydra's Grave is your basic dungeon complex, built with the resources of three eladrin houses. The following are constant features that can be found in almost every room:

• Glowing motes of light, that as far as Grynn can determine provide a cold illumination in most chambers, but mostly seem to be an effect of heavy magical "bleeding". The light is just a useful side-effect. I kept pressing the fact that they were unharnessed magical residue, and I'm surprised that no one has thought about trying to channel it as part of a magical effect or ritual. I havent decided on a hard effect for these, instead waiting for some player input and creativity on its usage.
  
• Illusionary walls that monsters like to come charging through, since the creatures that have been there awhile (mostly carrion sprites) have learned which walls are real, and which are false.
• Roots that grow through the walls and ceiling. The basic function of these is to ramp up fire-based attacks (which Maev has with fire seed, but even Grynn is packing some alchemist's fire). Big ones can be used as cover, but if you are in a square with a root that gets lit on fire you take fire damage. Very simple and easy.
• Crumbling pillars that could be used for cover and/or pushed on top of adjacent monsters. I put these in a lot of rooms. Sure, the eladrin put a lot of effort into the place, but after a thousand years and roots growing through everything, something is going to give. I would run this as a Strength attack/check that deals basic damage and can either prone or immobilize and prone depending on size.
• Piles of bones or stones that act as difficult terrain. Simple but appropriate. Pillars that get knocked over would count as such, as would the larger undead baddies.
  
• Sarcophagi that could be used as ranged cover, or stood upon for a simple melee attack bonus (yes Josh, you can haz higher ground). They are also difficult terrain. Sometimes, I like to have monsters spring out of them (mostly skeletons or ghosts).
  

However, I did add some unique features in specific chambers:

• A massive shard of ice that characters trained in Arcana could use to make powerful ranged attacks. Grynn was able to pull this off in session three. The shard also granted resist 5 fire and slowed creatures that werent proficient with cold-based magic.
• There was a room filled with wolf spirits that made it so that if you hit a flanked creature, that it was knocked prone.
• A room with a charnel pit that imposed a penalty on living creatures, granted everything inside concealment, and also ate healing surges.
• A room with two walls filled with demonic remains that did random shit to creatures caught between certain sections: sometimes it was energy bursts, sometimes it ate energy attacks. Other times it caused a creature to randomly attack someone if it beat their Will defense.

Thats it, so far. At least, all that I want to reveal. The party has dealt with all of this shit already, and I dont want to reveal features that they havent seen, yet.