The most recent room was here
Most Obvious Thing:
The north , south and west walls have trench of ash in front of them with odd looking bare golden trees emerging out of them.
There's a 50% chance when the room is entered of it either being of Flame or of Ash.
If it is of Flame then there's a great cloud of burning gas around the branches and roiling along the ceiling. It burns like a dirty gas flame, mostly blue with ribbons of yellow and the branches of the trees still visible through .
If it is of Ash , there's no flame cloud, but a cold wind will rise from nowhere, whipping along the surface of the ash trench , making a simulacrum of snow drifting in the snow.
Details available with further consideration:
The reason the trees are odd looking are they entirely (and artfully) constructed from human bones coated with a valuable amount of gold. They also might be hot enough to cause burns to the touch , depending on how long the flame cloud has been present (see context).
The flame cloud , if present., appears to have purple flames among it to, and these resemble the wings of large butterflies (2 foot wingspan)
The ash wind , however, instead has periodic movement under the ash , like something is swimming in there (which something is).
Every 5 rounds the flame cloud dissipates , and the ash wind starts, which then continues for 5 rounds before the flame cloud bursts into life again. This will cool down the bone trees so they could be touched without causing damage but then cool them down to the point they will cause damage from being so cold.
This is a ludicrous scenario as far as read world physics is concerned but there is at least 3 sources of bullshit involved , the bones are slightly haunted , belonging to former monks whose remains have deteriorated beyond the state of the ones in room 8, magic is involved in the construction, there's elemental present in both the flame cloud and the ash.
Assume the trees do 1d6 fire or cold damage to anyone touching them on the 4th or 5th round of the Flame/Ash and d.m call on the possibility for wearing protective gear and getting less damage, or making prolonged contact on rounds 3 (maybe a d4?).
If a branch is broken off from the bone tree , this interferes with the magic that makes it cool down/ heat up and it will stay at its current temperature for 5 minutes. This is just to reward any players who think of breaking off bits of the tree to hit the guardians of this room with them.
Context and details:
Anyone stepping or falling in the trenches will sink extremely quickly to the bottom of the room through the ash.
The ash trenches are 7 foot deep and continue a "square" (see map) underneath the middle of the room, so if you were to fall into the trench and try and walk along the bottom and climb up when you hit a wall , you would have a ceiling over your head and be in trouble.
The trees go all the way to the bottom of the room, with 7 feet above the ash and 7 feet concealed.
The room guardians are Flaming Glass-body Butterflies and Razor-boned Skeletal Eels , lesser known Elemental spirits that can be compelled with magic to hang around and attack people messing with an location or object.
Which in this case is the bone trees and the ash trench.
The Butterflies only manifest when the flame cloud is present, and when it dissipates, their wings disappear and they cling to the ceiling and become inert. Their bodies are difficult to see without the wings, and someone would have to be specifically looking at a particular patch of purple fire to notice the lingering visual disturbance of the body clinging the ceiling afterwards.
If the bodies are taken outside the room the butterflies can't manifest in them. They valuable as weird trinkets, but more valuable to alchemists or wizards that deal with elementals or summoning.
They attack by swooping down from the cloud and leaving a flaming trail behind them.
There's a total of 8 present. When the flame cloud reappears, any damage done to the butterflies is healed and any defeated ones return to life, unless their body has been removed from the room or destroyed with cold damage (of which they take double damage)
Their ash equivalent are 5 feet long skeletal eels with delicate looking (but with steel strength) razor sharp ribs that extend out as they dive from one side of the room to another, slicing anything in their path.
Once the ash wind is about to dissipate, they will try to be already in the ash itself when this happens. They will become inert eel skeletons when the flame cloud present. Like the butterflies they will restore any damage or destroyed eel when the wind returns, unless that particular body is destroyed with fire or removed from the room.
Their bodies are valuable in much the same way as the glass butterfly bodies.