Energy

Energy is a ScrapTD resource which is used in battles (1 each battle) to get resources, which in turn allow you to buy several ingame upgrades.

Importance of energy
Energy allows you to get resources at a battle (Bricks and Magnets if you win, otherwise only Bricks are given). Without it, you wouldn't be able to upgrade anything. NOTE: You still get (or lose) Trophies without Energy, as well as with Energy.

How much does it take to recover?
To get 1 Energy, you need to wait 2 hours.

And... how many resources do I exactly get?
Bricks are calculated with this formula:

$$log1.5(totalscrap)*3*1.1^{arena}$$

To calculate scrap earned based on bricks gained, use antilog with base of 2.

Magnets depend in the arena you are, and only if you win.
 * Arena 1: 10 Magnets
 * Arena 2: 11 Magnets
 * Arena 3: 12 Magnets
 * Arena 4: 13 Magnets
 * Arena 5: 14 Magnets
 * Arena 6: 16 Magnets
 * Arena 7: 17 Magnets

Maximum Brick Gain
After all, you'll figure out the longer the match (aka more Scrap) the bigger the amount of bricks gained.

That's why some teams have decided to invent a farming method to get the most bricks possible, and without the risk of losing trophies.

Brick Farming Method
First note that you'll need 15 Minutes for this, as it is the time a match can take at most.
 * At first, you put two Square Blues and then spam Circle Blue until you can afford Gatling Gun.

WARNING: This is almost always an agreement between teammates, don't expect a foreigner to do this.
 * Then, put 1-2 Gatling Guns and spam Square Pink until you can afford Defense 3.
 * Put 2 Defense 3 towers and spam Banana Hole, one every 2 seconds, until you can afford Double Pain.
 * Fill two or three spaces with Double Pain.
 * Get to fill all the board with Tesla Tower and Gatling Gun II without killing your teammate.
 * In the end, you can just spam Not Too Fresh, as there are enough Teslas to kill all the barrels which come. You can change it for some Chromes too, but again, they have 4x scrap value but 4x health too, so it's just best to stick with Not Too Fresh.