I recently picked up a bunch of Double Dice (dice inside of dice made by Koplow Games). The d10 inside a d10 is great for generating a 1-100 spread with a single roll (and it works much better than those wonky d100's with the clear outer layer and a ball inside with 100 printed numbers). But what to do with a d20 inside a d20? Or a d12 inside a d12?
Two thoughts:
Fatility! Stealing a cue from Mortal Kombat and EPT, if you a roll a natural 20 and the inside die is also a 20, you instantly slay whatever you are attacking. Conversely, rolling the dreaded double 1's must have EXTREMELY dire consequences. At bare minimum, we are talking a broken weapon. This is your chance to get creative with the critical fumbles - with only a 1 in 400 chance of occurring, the double 1 should be epically bad. Variant - For an even deadlier game (this is the rule from EPT), the inside die only needs to be a 19 or 20 to achieve the same result.
Exploding Damage Dice: If you roll the maximum value on a die while throwing for damage, you also add the inside die. This seems like a nice way to add an exploding dice rule without necessitating extra dice rolling! This could really speed up play by increasing damage done in combat without increasing dice rolling time. This might be really good for games like D&D 3e and 4e in which combat can take a LONG time.
Okay, I'm going to throw the die in your court now. Can you come up with any cool uses for dice inside of dice? I have a d20, d12, d10 and d6 in this format.
