I was referring only to the fact that you can't have both a Felguard and Ruin. I linked my optimal build earlier, and it's a 0/40/21.

It doesn't proc? That's certainly weird, since it procs off any other fire-based targetted projectile attack (but not fire-based melee attacks like a fire elemental - for whatever reason). I guess they simply don't want a talent deep in a talent tree to make or break a fight.