That's fair: I made a token effort to match the theme by surrounding the arena with a wall of lightning, but that's admittedly a pretty weak connection.
I'll make sure to do a telegraphing pass when I do my revision. Everything that spawns has at least a short fade-in period of some kind, but some are longer than others, and I suspect that some *look* like they've spawned before their collision is actually active. Do you recall any specific effects that were especially problematic?