The Blight Anchor thread in the General forum got me thinking about a few areas being placed around Istaria that will occasionally be invaded by the Aegis.
Take the outpost north of Harro just outside the Eastern Deadlands for example. What if every once in a while the server would spawn an unknown number of Tier 6 Aegis a distance away from the fort who would then attack it in waves? There could be a number of areas like this placed around Istaria for various tiers. That's one idea, anyway.
Despite ultimately being shut down, the thing I loved about Tabula Rasa was that various outposts would be occasionally attacked by a force of unknown strength and you would have to thwart off the attack to keep the outpost.
Now, I'm not suggesting something of that complexity be done, but perhaps it could help return some of that 'event' feel to the game. I can definitely see this being a bit of a job as far as coding is concerned, but imagine this scenario:
There's an outpost that can offer some neat benefits (I dunno, maybe you could get a unique combat buff from an NPC there or something). This outpost gets attacked by Aegis. There is an NPC 'commander' in this outpost that would need to be kept alive, if the players fail this protection and said commander dies, the outpost's spawn table will be swapped for an Aegis one and general Aegis mobs will spawn along with an Aegis commander that the players will have to kill to take the outpost back.
Now, this outpost wouldn't be used for any crucial quest or anything, because that got annoying as far as Tabula Rasa is concerned. It could just be one of those things that 'would be nice to have'.
It's an idea, anyway. :P At the very least you'll be able to give the players something to defend (something worth defending, hopefully) and help ease the tension of the long missed events.