Devil Sweep Techniques

The devil sweep rankings got reset, and so this is probably a good time to write on this event. I barely got to the top spot with a 63 rounds lead, and am rather upset that it got reset. We received no notification, warnings or whatsoever, so my guess is that they will probably do this every year. For those who are new, I had written a beginner's guide here :
http://sislandec.blogspot.com/2010/12/devil-sweep.html
Enough nagging, on with techniques. There are 2 main techniques that I use :

Herding
Many players already know this, or use this technique, but the first time I hear the term 'herding' is from Bear. So I'll give him credit for naming this technique.
Round the week, you kill devils that are 20 squares or further. You do not kill those devils that are near. As the far devils get killed, there is a chance that it will reappear near you. When you repeat this, you can get a significant herd of devils near your city. That way, when the event start, you can use kill those near devils to complete each round quickly.

Preemptive Attack
This technique is probably more suitable for big players, or for smaller players who received aids.
The devils for each round is random, but sometimes you run low on a particular type. As the devils get further, you may want to send attacks out for next round before the current round is completed. Unless you have 13 extra heroes (one for each type), you will probably have to guess what the next round is. But random guess doesn't do so well. If you have a dark knight that is near, you don't have to make a guess on that type. Instead, you send preemptive attacks only for those types that are further.
So if you see that you have no seastrider near you, you may want to send an attack for that type. You want that attack to land only after the current round. So when the next round is revealed, and it includes a seastrider, you already have a good head start. If it does not, you have the option of recalling that attack (especially if the next seastrider is significantly further), and sending another hero to that same seastrider, again landing only after the current round.