Would you be alone when the Armies of Hell come down to destroy the world of Sanctuary? As the saying goes, "Only fools and those who fancy themselves brave" face their enemies alone. Who will stand beside you in the war for Sanctuary? One of your followers, of course.
You would be able to choose from the three followers at various times during the war in Diablo 3. These are Templar, Scoundrel, and Enchantress. Here are the key features of each of the followers:
Templar Kormac is brave and can take on enemies with a subtle strategy. Kormac taunts enemies and makes himself the focus of their attack. He punishes by crippling enemies or slowing down their attack. Kormac heals with his faith. He can call the healing powers to spring you back to your healthy state with your natural state resource regeneration and healing. Kormac answers to the call of 'justice' in his own way. He is ferocious as an attacker and can cause very bad wounds to the enemies.
Enchantress Eirena can cast magic spells that would leave your enemies permanently in a trance. She can also use her magic to make your enemies fight amongst themselves. Her favorite are the power waves to blast through enemies and send them flying into the air after the point of impact. She can project force shields to protect you from any danger and also turn a strong attack against enemy forces.
Don't forget that apart from the followers, you also have to choose your weapons wisely. Your followers and weapons would be your 'true friends' in this battle against the Armies of Hell. You can choose one of the three artisans: Blacksmith, Jeweler, and Mystic, to help you with your weapons. The only advice is: Don't go empty-handed and don't go alone.