Most of the times abilitys that cost Energy are more powerful than abilitys that either do not cost Energy or build Energy.
There are a few ways to gain Energy:
1. Abilitys - Every class in Family Guy Online starts out with an ability to build energy, meaning that every time they will use that attack they will gain a certain amount of Energy depending which attack they use.
2. Consumables - There are a few consumables in Family Guy Online which can be used to gain Energy such as Peter's Homemade Energy Drink. These consumables can be obtained through tasks or loot from fallen enemies.
The Energy Bar is a thin bar found under the abilitys bar in Family Guy Online.
The Energy Bar shows each player how much energy he/she has and what is the maximum energy he/she can have at all times.