onslaught realm. You enter this realm to open a vault that has rare items,recipes, resources. To open the vault you have to hold down a control point for a full night without the enemy disrupting a timer or a process. You build fortifications around this point to protect it. As soon as night falls you have wave after wave of enemies trying to destroy your fort. Each wave stronger than the other. Just before dawn you fight a boss that can nearly decimate your fort. You make it to dawn it unlocks the vault. Possibly rewards like turrets and sentry guns to allow you to experience even harder onslaught levels with even better quality loot. Allow for other players to help. Could even adapt idea for team vs team pvp.
