Purple boosters are defense boosters (placed in friendly cities), red boosters are attack boosters (placed in enemy cities). Do not place the boosters without knowing what they are for.

Why?

If you put a booster without knowing it, you can ruin a war in your club.

How should it be done?

Your club is a great ally, ask what each one is for if you have doubts. A brief summary:

DEFENSE BOOSTERS
bomba3 The pump or accelerator recovers energy faster.
fracaso3 The dud serves to divide the points in the city you put on.
paraguas3 The umbrella serves to protect you from general attacks.
ATTACK BOOSTERS
bote3 The jackpot serves to double the points in the city that is placed.
vampiro3 The vampire slows down the energy that is recovered.
Potenciador Congelación The freeze prevents the city from attacking.
ladron3 The thief booster steals energy from the city to which it is attached.