Drone

 is a unit  and part of the base set. It produces gold per turn.

Strategy
The humble  is one of the most important units in Prismata. Their Ability to produce Gold is the key to building up your attack, your defenses, and everything else in between.

s cost 3Gold and Energy. This means that s will pay back its Gold cost in 3 turns. Buying an Engineer and then a means that the  will pay that total purchase in 5 turns.

How many s you should purchase ultimately depends on the Random set. The most important factor to look for is the biggest blocker (also called the absorber) in the set. Bigger blockers can absorb more damage, which makes you want to avoid making attack too early - if you do, your attack will all get absorbed. This makes you want to buy more Drones before switching over to making attack, so that you can get over the absorb barrier more easily.

A common beginner mistake is to continue buying s in the mid and late-game. Once you are doing more damage than your opponent can absorb, you should be focused on buying attack and only buying Drones if you happen to have leftover, and even then it might be better to buy an Engineer as Engineers have the same  for a lower cost.

s can also block in emergencies. If you don't click one of your Drones, you can use it as a Health blocker. This can be a good play if you would otherwise be breached and want to keep a high-health absorbing unit. Alternatively, the green resource allows you to convert s into more efficient blockers such as Forcefield.