How about it's becomes more common the more CPU that is used (the chance of it spawning should be 0 or almost zero until a certain threshold is reached), I'm talking about the lag that does not cause minecraft to crash due to out of memory error but just lag alot; like when there are a lot of mobs produced by an exp farm left over night (caused my frame rate to drop to 0.5 fps but did not crash) also this may seem ironic due to the example I gave but it would be best if the lag were to be made by redstone or something else rather than a mob spawner as it's too easy to do that.
Also when missingn0 some glitches should appear like possibly block textures Are all swapped
Pokemon all start flying in the air with fucked up animations and pieces like this;
Only when you defeat or capture missingn0 does the world turn back to normal