The "percentile", or "10d10" dice are still found as a standard component of most polyhedral dice sets. But, I've yet to see use of them in my (albeit limited) experience with D&D 4e. Are there powers or other rules I'm not aware of, that still use these?
Nope, not in the WotC books, anyhow. It's possible that someone slipped a percentile dice requirement into a third party supplement, but there aren't even tables that use percentile dice in WotC's stuff. The new red box Starter Set comes with six dice -- no d10 with extra 0s after the digits to serve as the 10s digit.
The Official Dungeons And Dragons Dice Set only comes with 1d10, so... I think that's a pretty good sign that it's officially depreciated from use.
I played the new Gamma World 7th ed.(at Amazon) as a one-shot this weekend and I had to roll percentile dice for the first time in a very long time, possibly since 2nd ed. Gamma World is based on D&D 4e, but quite scaled back (no healing surges, no daily powers, no bull rush) and a little weird. From WotC:
The D&D Gamma World Roleplaying Game offers hours of rollicking entertainment in a savage land of adventure, where the survivors of some mythical future disaster must contend with radioactive wastes, ravaged cities, and rampant lawlessness. Against a nuclear backdrop, heroic scavengers search crumbled ruins for lost artifacts while battling mutants and other perils....[Gamma Wold] is a complete, stand-alone roleplaying game that uses the 4th Edition D&D Roleplaying Game system as its foundation.
The percentile rolls were part of rolling for my equipment during character creation. I rolled a '1' on the random equipment table which meant "roll twice on the
Ancient Junk table" and the
Ancient Junk table needed a percentile roll. So I rolled a 70 and a 12 and acquired:
- 12 - a twenty pound dumb-bell
- 70 - a gas grill (with a tank of propane)
I wound up playing an 8' tall stuffed teddy bear that threw the dumb-bell as its heavy two-handed ranged weapon and gave bear hugs to bad things. I had a blast.
The explanation of "Game Dice" on p8 of the PH includes the following,
You can use d10s to roll percentages, if you ever need to. Roll 1d10 for the “tens” and 1d10 for the “ones” to generate a number between 1 and 100. Two 10s is 100, but otherwise a 10 on the tens die counts as 0—so a 10 on the tens die and a 7 on the ones die is a result of 7 (not 107!).
I'm still searching for an example of where they are needed though! Good question :)
Not an official use, but our DM rolls percentage dies on all critical failures(PC and monster, weapon and skill checks). If he rolls a 90+ you get to reroll the die. 10% and below something bad happens. It adds a bit of randomness...and gives the percentage die some love as they do often feel neglected.