I hunted down 400M Assassins to 188M and it took me over 750 turns, where as, DMing give or take 10M Defense Units would only take 9 turns and kill the same amount of units as the 400M but taking a ridiculous amount of turns less, not even including the fact that you are DMing 10M units..
My suggestion would be to make it so you kill more Assassins for the amount of turns used.
I do not play Ascended very often, so I may be mistaken about how this works but even so. The amount killed in comparison to turns used needs to be adjusted at the very minimum seeing as we are on the topic of 'updating' Ascended.
![Think :-k](./images/smilies/eusa_think.gif)