What dice do I need to start playing D&D?
One standard seven-dice set covers everything: d20, d12, two d10s, d8, d6 and d4. Every CritStones set is a complete seven-die set, so any one of them is enough for your first session.
How do I read the two d10s together (percentile roll)?
The d% (00 to 90) gives the tens, the d10 (0 to 9) gives the ones: 70 and 4 is 74, 00 and 7 is 7. The special case: 00 and 0 together reads as 100, not zero. And when the single d10 is rolled on its own, the 0 face counts as 10.
What is the d20 used for?
In D&D and most similar games, nearly everything important: attack rolls, saving throws and skill checks. At a D&D table it is the most-rolled die of the seven, which is why you can buy a d20 on its own.
Can I use a spindown d20 from a card game?
A spindown has the same twenty faces, but the numbers run in sequence around the die instead of being balanced across it, so any tiny imbalance skews results in one direction, and many tables will not accept one. For anything that matters, roll a true d20.
Do different dice materials roll differently?
They feel and sound different far more than they roll different: weight, balance point and bounce vary between resin, metal, glass and gemstone. The full comparison is in Dice materials, explained, and balance gets a proper answer in the 10,000-roll balance test. Keeping any of them in good shape is covered in Caring for your dice.
Which dice do wargamers actually use?
Mostly many copies of one die: pools of d6s in most mass-battle and skirmish systems, d10s in others, which is why wargamers often buy several matching sets.