Boosters used purely for sale. Boosters' stats are extremely low so using them in your army is useless.
Maximum profit can be gained on "Mega Sell" event (starts on Wednesday and Sunday (at 11:00 UTC/GMT +3).
There are 2 types of boosters: Golden Pig (T2 grade II) and Precious Pig (T2 grade III)
Two Golden Pigs evolve into Precious Pig.