Ah. Do you have Extra Utilities? If so, a few pieces of cursed earth will spread to the entire ritual area, and spawn mobs in relatively large quantities, and can be turned off by applying redstone signals to lamps. Natural sunlight destroys CE, but artificial lighting doesn't. Plus you get the neat Division Sigil, unless you get CE from someone else on the server.
Also MFR has conveyor belts, if you'd like a larger mob spawning area and can't fit it all under the well. You can have them spawned, dropped onto conveyors and hauled beneath the well. They can even go up slopes.
Also MFR has conveyor belts, if you'd like a larger mob spawning area and can't fit it all under the well. You can have them spawned, dropped onto conveyors and hauled beneath the well. They can even go up slopes.