I dont have access to the game right now but I can at least tell you the skills I use. I Dont have a main skill - but rather three. I use a combination of Armageddon, Fissure, and Volcano - more or less depending on what type of character I am fighting. If I remember correctly armageddon damage is about 16K... The rest I can look for later. And as far as Darkmatter goes - its easy to kill with armageddon, if you know how to aim it and you spend a lot of time learning how it works. YES i said aim. The way you walk, tele, run, and the angles you take ALL can aim the random hits [more or less]. Another fun thing with fissure is it stuns characters running through... so four thousand damage turns into tens of thousands after the fifteenth hit or so.
The build works. Its just not one of those 'make it in three days and kill people in four' type of builds. It took me a while to learn how to use it. Especially with eight hot keys - still wishing i could use more.