At the beginning of the game, minions do not spawn immediately, so gods can have enough time to kill monster camps and get buffs. After a certain period of time, an announcement will be made, along with a message appearing on the player's screen that the first groups of minions have spawned.
Although it may seem obvious, minions are also considered as allies, and can be targeted for buffs.
It is obvious which minions are which. Every time a group of minions spawns, the melee minions will charge into the fray first, while ranged minions support them from the back. Every group of minions will have a large minion that has increased health and damage.
Very often, a tactic among players is to let minions go attack towers first, while players use their abilities and attacks to further damage the tower, without taking damage because of the sacrificial minions.
Minions also have a "passive" to always attack the closest enemy god that is attacking an allied god within a certain area. You can tell when minions are attacking you as they will have 3 large yellow exclamaition marks flash above their heads. Also, killing minions is the fastest way to gain levels and gold, as they have fairly low health and are quite uninteliigent, so they will not know to retreat or wait for backup.