Imploding Encounter Dice

Here's a simple and fun way to make random encounters more varied: have the occasional multi-way encounter.

How it works:

Roll a random encounter on a d6, as is standard, except encounters happen on a 1.  

If you get an encounter, immediately roll a d5.  On a 1, you get another encounter...and roll a d4.  

Keep imploding the encounter die down to a d2, then optionally keep rolling until you don't get a 1.  If you really like this idea, have the dice implode faster, from d6 to d4 to d2.  

Important: The party doesn't have to be in the middle of these encounters.  They could just as easily run into a group that's encountering another group from another direction.

Make reaction rolls as normal for each group the party encounters...as well as every pair of NPC groups that also sight each other.  Yes, the players might wander into two NPC parties negotiating, fighting, or just passing each other by.  

These multiple encounters may not all happen at the exact same time.  Maybe do one first, then have each successive encounter occur after a minute of conversation or a round of combat.  

This may sound excessive, but it makes logical sense if you think about it.  NPCs must have their own random encounters, and two groups encountering each other means at least twice as much noise, and more doors and hallways in sight of the two groups.  Encounters beget more encounters.