I love summoners, but dislike mages for the same reason I dislike nova: annoyance
Mages...it's not the crappy damage, any extra crappy damage helps. It's not even the blocking...it's the fact that i can't cross 2 screens at faster than a crawl without the lot of them disappearing and having to resummon. Until can move by teleport, I am avoiding mages.
Poison Nova...in hell, seems half have such high resists it doesn't hurt them much, many more are immune, and about 1/4 it takes down quickly. However by the time I take anything down with nova, something is dead already, and find all i did was slow myself down not exploding corpses. I also get hurt a LOT more. Again, if have enigma to teleport around periphery novaing everything, think would be much better. Nova/CE though don't mix imo, probably not just me.
Golemwise....1 point clay slows bosses nearly as much as 20 with +skills....and it is amazing against bosses. At every other time, find fire is better at keeping me and skellies alive, because that aura seems to draw them to it unless skelly is beating on monsters or i stand nest to one. Also, keeps drawing the crowds, which is nice. Also....NO golem really does any damage in hell. Iron's thorns rarely get hit in a crowd of skellies, fire goes against high fire resists with a low attack rating and doesn't hit that much(1 maxed skelly does more damage than 1 max fire golem in hell)...gumby hits for 20.
You have about 60 points to spend after maxing skelly and mastery though. Lot of choices, none of them very good. My favorite is a huge corpse explosion radius and a fire golem aura big enough to poke enemies offscreen and draw them in, but no reason not to max mages given choices.....just really dislike having to let them catch up or resummon.