In a nutshell, the event is Qliphothic creatures vs Lemurians with the city caught in the middle. Qliphothics are opening portals, which need to be shut down. The Lemurians are building some kind of towers, which need to be shut down. The Colossus, a giant cosmic skeletal chicken, spawns in three locations around the city.
The daily missions are one for Qliphoths, one for Lemurians, and the Colossus, but the Colossus is also an open mission you can do nearly unlimited times. I guess you can roam the city and take out the Qliphs and Lemurians without getting the missions too. In my experience, you need teams for these fights, but maybe a DPS toon can handle them.
If I had a character that they suited, I'd probably like the dozen or more various animal skulls, but it's a pretty dull event, imo, and not fun like the holiday events or even the Gulch event.