Ohoy!
Almost every game that introduces time limited events makes the same mistakes.. And it's frustrating and easy to fix.
The what:
You introduce an event with for a limited time that requires people to team up. You make people dependant on others.
Benefits:
Increased cooperation. Friendships. Fun together. Yadayada. It's easy to see why it's great!
The problem:
Your event has extremely limited replay-ability. There is no reason to do it twice. People do it once for the great rewards and unique loot you promised them, and then return to do other stuff.
This is the case in SoT, WoW etc. etc. Every game makes this mistake.
Since you limited people to need other people it creates one very annoying thing.
PROBLEM!
If you are not online the first weekend of this event, you will NEVER find anyone who wants to do it with you. You will waste a huge amount of time searching for people and it becomes tedious to do and a bad experience trying to get that epic loot....
The solution:
Increase replay-ability so its fun to do, to re-do and to REDO again! For the limited time span your event exists you want people to play it no matter how late in the cycle it is. Especially if your lifespan is 2 weeks (which is at least 1 week to short).
You can do it like this:
The best: Random epic rewards. Everytime you do it, you have a chance to get something new / rare / different. It's an easy psychological trick that mobile games do. It helps you do the exact same thing over and over again in the hope to get something.
The technical: Merge servers in event zones (worked in WoW). WHen people enter the area of the event, make sure you merge them with servers that has people waiting. SoT is very empty of people, and thats not good trying to do events.
The easy: Achievement mechanic:
Make an achievement for killing the beast 10 times.
Other: Add a world information where everyone on the server can see people waiting in the area so they know someone is trying to do it.
I am sure there are other ideas. This literally took me 10 minutes to come up with. But something is needed. I never got to kill the shark, went online 3 times to try for 2 hours each. Fail. And sometimes you have some IRL stuff that you need to do. It sucks I agree.
Hope someone important reads this and embraces the idea of optimising it, as it seems like we will see more timed events in the future of SoT!
Farewell.
