I was thinking it would be kinda cool if rogues could set up traps that triggered when the mobs stepped into them. You could get the trap components out of chests and then combine certain pieces to make different types of traps. higher damage stuff would come out of higher chests obviously.
Implementation into the game could be pretty simple, just like a symbol of flame or fear, a marker hangs in the air for where the trap is and shows an active area, then once mobs enter the animation goes off for the type of trap created, either acid, spikes, fire, fear, paralized, death, etc.