As you rankup through the mines there is less and less to do. It gets pretty boring after a while of constantly mining and maybe some PvP and building. I think we should integrate some spawners. Make them extremely pricey so it wouldn't be a thing that overruns the mining aspect. If you could integrate cactus farms into the system, why not also put in the spawners. The items wouldn't have to sell for much and the mobs wouldn't drop mob dust since they would be placed in the Plot World. I don't recommend making the spawners something that has to be bought through /buy because it would be P2W. It would be great to add Mob hoppers which also kill the mobs automatically just to add in the AFK aspect as well. It would be nice to see this change come to the server and make it not only more enjoyable for the player base but also as another way to change things up and make some money.
I don't see the point of adding auto kill, you should make them fall to death... Maybe another cool feature would be that for every mob you kill you get it's head, you can dump the heads into a couldron and when you have enough heads you can get a mask for that type of mob that can give you a different sort of ability when you are wearing the mask. I don't think a spawner should cost trillions, but I think it would be better to make different tiers, so the cheapest one for example would be a chicken spawner for example.