Tracking ammo in White Star
Monte Cook introduced a wand depletion mechanic on his Dungeon A Day (subscription only) blog back on Sep 29, 2009. Looking around the internet shows the concept was floatring around at sometime before 2007 (see reference to the Wands of Diminishing Returns rule). Basically, instead of tracking charges or arrows or whatever, you roll a dice. On a 1 you use the last shot (or decrease the dice or something). So instead of the RAW 20-shot power cell ammunition for laser weapons I am introducing the following
Cell is depleted after the current use when rolling a 1
Nearly Empty Cell: 1d4
Used Cell: 1d6
Low Quality Cell: 1d8
Typical Cell: 1d10
High Capacity Cell: 1d12
Freaky Alien Artifact used as a Cell: 1d100
Notice I did not include the d20. When using this rule, Mercenaries and Combat Robots bump up the next higher depletion dice to represent their better use of ammunition. Brutes are too brutish to gain a benefit. So a High capacity power cell in the hands of a merc depletes on a 1 on a d20.
An alternative rule would be to decrease the depletion dice one step every time you roll a 1 and the device is truly empty when rolling a 1 on a d4. With this alternative, you start with a d12 and when you roll a 1 you keep going but now you roll a d10. There may be a friendly indicator on the power cell to alert the user about the quality of the cell. Using a weapon while on d4 is somewhat risky! Furthermore, just for fun, if you roll a 1 and then roll a 1 on the next use, that means the power cell malfunctions – BOOM! take 1d4 damage. Just a thought…
Finally, I would introduce a Freaky Alien Artifact that can be hacked as a power cell that uses the d100 for depletion (and you can use a 1 or a 1 and 2 for depletion). Do not apply the bonus for Mercenaries and Combat Robots here since this alien tech.