Everyone who does at least 1,000 healing actions and 2,000 overall actions (including both attacking and healing) is rewarded with Cash, Experience, and an item drop when the Raid Boss is defeated, this is known as the minimum actions required in a Raid.

However, the chance to get a Superior drop is generally random, but you can improve your chances at getting some loot by performing more actions.

There are only two special conditions under which a player will be guaranteed a Superior item:
Achieve Victory over your first self-created Raid Boss of a new event. Note - minimum actions are still required. Or, complete the most actions for any Raid Boss instance after that.