All of that said tonight I am going to talk about one of the House Rules that I've been running in my games for the last couple of years: the exploding damage die mechanic. I first ran across the concept when I picked up a copy of the Savage Worlds game system. In that game whenever you rolled the maximum amount on a given die you got to roll that die again, adding its result to the initial roll. If you were lucky enough to roll the maximum result again you added it to your total and continued rolling until one of your die results were less then the maximum.
What I liked about this mechanic was that it made combat incredibly dangerous which in turn made my players more thoughtful about how they proceeded but when I initially tested the mechanic in my Dungeons and Dragons game there was a problem. If I allowed the mechanic to work at all times, with all damage rolls, then combat became impossible as every attack was capable of taking out anyone at anytime. And while it's all well and good when you're first level and you take out an epic level creature the same can't be said when you've worked your way up to eighteenth level and a measly goblin kills you with a sling bullet.
In order to remedy this problem I was forced to use the mechanic only when a player had rolled a critical success. This still made the combat dangerous, but not to the point of making it moronic to even enter combat.
Now the aspect to this mechanic that I had not anticipated was the way that my players crowd around the table when someone starts a series. They're doing the math and acting like every roll is their own - and when the tables turn! My god when the tables turn it's even better!
Critical Damage: For critical damage results we will be using the exploding damage mechanic. After confirming a critical success, roll your damage die, if you receive a maximum result, roll that die again. For example, Tim’s Fighter confirms a critical success with his short sword (1d6). Tim rolls 6, 6, 6, 6, 4 ~ ending his exploding die rolls ~ and he has a Strength modifier of + 3. Thus his total damage is 31 (6 + 6 + 6 + 6 + 4 + 3 = 31)