Wands Without Charges

Timrod has a post about wand degradation. Basically, making wands get used up without having to track individual charges. This is something I've tried a couple times before. I think I would go with fewer dice rolls, myself. So I suggest this alternative:

When a character uses a wand, roll one die. If the maximum result is rolled, the wand is half-used. If the maximum result is rolled for a half-used wand, it is now drained of power.

The maximum result depends on the die used, of course. For wands, you'd probably want to use either a d20 or a d12. A staff traditionally has fewer charges, so a d10 or d8 may be in order. A rod or a cantrip wand would use a d6.

A drained wand can theoretically be recharged, or a caster could attempt to wring one last use out of the wand. Make a reaction roll: on a Very High result (12 on 2d6,) the wand works one last time; on a Very Low result (2 on 2d6,) the wand explodes for 3d6 damage.