Each member of a city can choose to send heroes on 2-hour quest to collect special event items for up to 25 steps. Steps are locked by Castle level (city locked) and Shopkeeper level (player participation lock). Once the heroes return, the player will receive loot from the heroes and receive a bonus loot round.
The loot count is then put towards the progression of the City Raid step which can be viewed at the top of the City Raid pop-up. Once the required amount of items are obtained, the step is considered complete. A notification will pop up informing the city that the step is complete. Once a single step is complete, the player must manually collect the rewards before the next City Raid or they will be lost.
Once all available steps are completed, the City Raid is complete (though the city can continue to play Endless Raid for Fame until the Raid ends)