In your guild's stronghold zone, there are four dragons, one in each of the four cardinal corners (NW, NE, SW, SE). Your guild can start an event to fight them that lasts 10 minutes either by using a golden bell (purchased on zen market, 500zen, 5 uses), or by talking to the Travelling Wizard that shows up at the stronghold near the large rock. He shows up randomly, but is there more often than not. If he isn't, just wander around inside the castle for a minute until he shows up.
1. Once starting the event, you'll have one minute to 'stage' before the dragons arrive.
2. Once the dragons arrive, you have 10 minutes to kill them. However, you can get almost 11 minutes, because after the first dragon dies the 10-minute timer disappears and a one-minute timer begins to kill the other 3 before they flee. So if you kill the first dragon at 9 minutes 59 seconds, you'd have another minute, bringing the total time to 10 minutes 59 seconds theoretically.
3. If more than 20 people are near any given dragon at the same time, that dragon becomes immune to damage. This is why you form two primary groups, one for north and one for south dragons.
4. You can see all four dragons' hitpoints as a % in the top-right side of the screen. This is important, and all players should be aware of this and be keeping an eye on it, especially after the two larger teams break away from NW and SW to head to NE and SE (see strategy below).
1. You'll want 30ish people at a minimum for two groups of 15, but the more better unless your active players are super OP. Form up at the keep and set up two primary teams. The best way to do this is to have everyone meet at the large rock in the middle, and two people are designated as 'team captains'. These two then proceed to call out names and when your name is called you move to them.
2. They should focus on dividing the support classes like Clerics (haste especially) and Oathbound Paladins evenly between north and south teams. Once that's done, they divide the DPS classes evenly as well. It helps if the team captains try to divvy up people based on their item level so that it isn't too lop-sided where north or south has massively more DPS than the other. If you have an uneven number of paladins or clerics, send the extra one to north team as the NE dragon is the strongest.
3. Once groups are set, the two large teams head to Northwest and Southwest dragon spawns. One person should have an alternate character at the keep so they can log that character in to start the event then switch back to their main.
4. When the teams arrive at the NW and SW dragon spawns, get everyone in groups except for the Paladins. Paladins' group buff dailies like the bubble and the group defense buff daily (will add in names for these later) will connect with nearby allies even if not grouped with them. This saves spots in the groups for the clerics to see and heal people since Paladins usually have the highest defense and HP and will die less than others.
5. Designate two to three really good players with solid DPS at each of the two large groups to be the 'cleanup crew'. The will be staying behind once the larger groups break off to clean up the NW and SW dragons.
6. Once ready, have the designated starter switch characters to their alt, start the event at the keep, then switch back.
7. During the dragon fights, keep an eye out for Dragon Empowerers. These guys spawn and buff the dragon, so you want to take them out ASAP when they spawn.
8. Damage the NW and SW dragons down to around 10% or a little less, then the larger groups break off and head to NE and SE dragons respectively. The cleanup crews, once again, stay behind. Their job is to keep the NW and SW dragons engaged and whittle their HP down to 1% while the other two dragons are being fought.
9. The large groups should by this point be at NE and SE dragon spawns. They proceed to DPS both of them down. Whichever one is damaging theirs faster should slow down/stop if they get it to less than 5% to let the other team catch up.
10. One of the two larger teams should be designated as 'first kill'. My guild usually has the North team be first kill, so the larger group finishes off the Northeast dragon, starting the 1-minute countdown before the other 3 flee. Ideally, all three of the others will be down to 1-2% anyway and it should be very easy to finish them off long before the one-minute timer expires.
Congratulations! I'm working on getting a video up for this soon. I have one on twitch but it was a rather poor run and I'd rather show what a more optimal run looks like so I'm not 'teaching bad habits'.
I'll make a better video later that is more coherent with editing and such, but here's a quick down and dirty that I pulled off my twitch. I run through the basic strategy verbally, but my game lags out really bad and I miss nearly all of the first dragon fight in my corner. There are 3 successful completions in the video IIRC, but they're messy. Our first two runs that I wasn't recording were much better, so I'll get a better run recorded soon and edit/narrate it properly. At least this will give you the basic visual idea for now.