Guild Aid is giving and receiving help from your fellow guildmates. You can make requests for XP to help level up a hero or gold to level up a hero skill.

By default you can only request each type of aid once every 20 hours, but if that’s not enough, your guild can unlock additional requests through their Guild Perks. It’s worth noting that even if you ask for aid, you’ll still have the ability to level up that hero or skill, but doing so may cancel your request and you’ll have to wait until it resets before being able to ask for aid of that type again.