I'm suggesting a new guild PvE mode, Guild Battle Royale. All the current PvE modes are getting farmed by players freqently, but the goal with this one is to make it a different and unique experience for the players. I suggest having a maximum limit at once per month in order to make sure people feel excited when actually doing this.
The way GBR works is that a guild collects various items (Quest items is good here) in order to enter. I want to emphasize that the number of items that the guild is supposed to collect shouldn't be small or easily accessible. This is supposed to be a shared effort that is extremely difficult for one player to achieve.
Once all the quest items are achieved, a message is sent to either Mazey or a GM. They set a time and a difficulty for the actual event. For simplicity's sake, I suggest having two different difficulties. The easier one is supposed to be slightly more manageable for free to play players (comprable difficulty to Monster Clash) whereas the more difficult one is actually supposed to be extremely difficult and require a lot of planning and strategy to complete. I suggest that all the mobs here are level 200, in order to reduce their taken damage and to work around the health cap. Also, an end boss with an event higher level would be a nice addition. With the new Monster Clash changes, there are more capabilities to create efficient PvE characters. The difficult mode is not supposed to be realistically doable with regular characters.
During the time of the actual event, a GM logs on and teleports the players to an isolated zone, where they proceed to start the timer and spawn all the monsters. If the guild successfully completes the run, the guild leader will be rewarded depending on the difficulty and the time they took to complete the GBR. Note that the rewards are supposed to be distributed between up to 10 players, and this is a once a month event at best, so the rewards should be sized accordingly. This could be implemented in the game or be running temporarily as an event.
This is all basically meant to be a new fun and interactive way to play together as a guild. It's also something that people make an effort to farm and something they have to look forward to. All the current in-game features are so easily accessible that they have turned into farming objects. Granted this is fairly similar to Monster Clash, but with Monster Clash running every 2 hours, it's really easy to get burned out on it.