Bomb
Drops a BIG bomb
Cannon
Deploys a powerful Cannon that shoots nearby enemies
Chill
Chills the ground, slowing enemies that step on it
Heal
Heals all friendly units in your area for 8 seconds
Rage
Boosts damage of all friendly units in your area for 10 seconds
About Squad Busters Spells
Spells in Squad Busters are items you can collect during games to give you a temporary boost against opponents. When found, they are a one-time use that can either heal or buff your squad, damage or slow opponents, and more.
Not all Spells are immediately available when you first start the game, however. In each world, there is a new item you can unlock by reaching a certain threshold of characters unlocked in that specific world.