Starting tomorrow and running through June 8th, multiple events will spring to life all across the city of Neverwinter, including cult invasions and dragon attacks. Players can even participate in a counter-attack to bring pain back to the enemy.
There are all kinds of rewards that can be earned by participating in the siege, including cosmetics, a battlefield medic companion, dyes, and a brand-new siegebreaker griffon mount.
Source: Neverwinter