Currently, many of the Zone events follow a similar theme , which is defend X Wardstones, kill X many monsters, close Y Rifts and then finally kill one or more Mega Monsters.
The event could be improved dramatically, if the final rewards were proportional to how many Wardstones were left standing at the end of the event.
Currently, these events are sort of ad hoc, in that there isnt much coordination between the players in the zone as to who does what, so what usually happens is that most of the Wardstones get destroyed with only 1 remaining, as there is no incentive or benefit in defending them all.
If there were, then players would need to coordinate amongst themselves as to who would defend what, and the end rewards if all Wardstones were lft standing , would generate incentive to defend them all.
The Event would still work as is , if there wernt enough players on , or nobody wanted to defend them all.

Also, fix up the Turretts on the Wardstones.
These things do so little damage to Mobs , they may as well not be there.
When a Wardstone is upgraded, then upgrade the DPS that the turrets do , so that a small number of players have a chance of fighting a large number of Mobs , if the Wardstone has been fully upgraded.