Wasn't kidding about making a custom minigame. Similar design to how the Fight Cave and Inferno work, as waves progress waves repeat but with new monsters added in and so on. 32 waves in total, the last wave being the three demons from the OSRS version of MA2. It takes about an hour to complete all 32 waves. I don't expect the difficulty to be too hard, however it may take a try or two to figure out the order to do things to survive to the end.