Siege Masters...how to get 500?

[Green_Dragon]

As this is the help section, this goes out to those who have already completed the
task of 500 Siege Master kills for the Rising quest or are very close to it.
Please enlighten those of us who have no idea how to ever complete this quest
because of those bots that are rare in game.
In your answer please say a little more than just how great your player skills are and
how bad the others. Rather guide those who are clueless about this and tell how focussing
on this bot that only appears as part of Rag wave 13 really works. Thanks in advance!