I'm not going to say your build is good or bad. I'll just tell you this much.
With Inarius your skills have to be close range or they don't proc the damage buff from the set. The only mage rune I found that works great with Inarius is the poison rune. Otherwise, you have to go head first into a bunch of monsters to get the damage buff applied to your mages. In other words, you can't just stand behind your mages and expect them to do any damage. It's similar to proccing Bone Armor. You have to take a risk and get close to monsters to proc Bone Armor. I can't count how many times I died because of that. Now, imagine trying to manage Bone Armor + Mages... you'll probably die twice as much.
From what I recall, the gem doesn't proc the poison buff.