Encounter Design: Battlefields

"You're fighting on an endless, featureless grey plain..."

Sounds like a pretty boring place to fight. What that encounter needs is some terrain. 

Possible properties of terrain features:

• Impedes Line of Sight
• Impedes Line of Fire
• Impedes Movement
• Hazardous
• Moving
• Altitude / Distance

Note that a feature can have multiple properties: a stone wall impedes LoS, LoF and Movement; poisonous bushes are hazardous and impede movement; tear gas might impede LoS and be hazardous and moving. 

I was going to differentiate between "active hazard" (as in something that aims and shoots at you when you're in the room) and "passive hazard" (such as a barrel of gasoline, or a pillar covered in sharp spikes). However, something that's actively hazardous is probably better thought of as a monster even if it's not alive or mobile. "Okay", you ask, "so what about Moving terrain"? That could be something like a railcar, an escalator, or an elevator. 

Hat tip to The Angry DM's Guide To Battlefields and Battlefeels and well as the scenario generation rules of In Her Majesty's Name.