* Consider upgrading your radius to kill enemies. The starting range of 40 makes it very difficult to get all 5 enemies
in one shot. I was able to get it with 60, but even that was a little close.
* Areas with 5 enemies close can be hard to come by at times, but I found that the chess boards usually had them
clustered pretty close. Usually 2 or 3 big heads/spitters and 2 or 3 kamikazes can be found there. Eventually get in
the middle of the shooter group with the kamikazes trailing and set off the bomb.
Might require later layers to guarantee enough enemies, but not too hard in general.