Yeah, I want to fit Sorc in eeeeverything. I love my summon.
If you have Linker, you also have Spirit Shock. Don’t forget that! I know it’s single-target, but you could spread that with a link, maybe? Not that that’s the best use for a JP, but it should work. I never tried since I never use that spell since I don’t have its attribute and it deals like 0 damage in my build, but unless there’s some unwritten restriction on it that it cannot be linked, it should be fine.
That said, I have characters (Clerics) who have endless cooldowns and can’t do anything in between and I hate that, so I fully understand your concern. Also I am jealous of your Silute cost of Marnox; until recently, he was up to 75mil+ on Klaipeda and only dropped now to around 55mil.
Honestly, my Necro (W1/Cryo1/Linker2/Sorc2/Necro3) is dirt-cheap. It’s by far the cheapest character I have and also the one which survives everything. The Necro-attributes are all super-expensive and very nice to have, but none are really essential. As it also means that all summons deal the damage, there is no reason to put much into any damage spell attribute since your spells deal close to nothing anyway. The only attribute really, really needed are those boosting Disinter since gathering corpses is a pain otherwise. But it’s a build that uses zero items (unless you want the cat, which I never, ever used and my Necro survives the most out of all my characters), you always have stuff to do with Ice Pike/Ice Bolt/Linking/Summoning Familiars and it’s definitely not a boring build. Also my Necro doesn’t use Marnox, she uses Helgasercle, who is - purely in my opinion - way better than Templeshooter, Froster Lord or Netherbovine (but apparently I am strange).
If you don’t want Necro, then things get a bit more difficult because Wiz2/Linker1/Thaum3/Sorc1/Shadow2 would have been my next suggestion for farming if you want sorcerer in it. But you don’t want Shadowmancer, so that’s an issue.
The builds of your guildie are super-viable, but don’t have Sorc in them.
I currently am making a test build to see how Psychokino and RC work with Sorc. Problem is that I’m not at RC yet (one more rank needed) and Psychokino just sucks really, really big time - I would have never expected it to be that bad. I thought it might serve as a mixture of Crowd Control with Raise and Heavy Gravity, like Ice Pike, while also be able to group enemies together like Linker, even without the shared damage. So like parts of both Cryo and Linker in one class. Yeah… no. Better take a rank in Cryo and Linker than wasting any on Kino. At least I can get my maps finished before I reset her.
I honestly cannot give you a surefire build that would work and that I tested myself. My friend tried Wiz3/Thaum1/Sorc2/Necro3 - again a Necro - and said it works well, deals more damage than a W1/Cryo3 or my build, but survivability is far, far less because of the lack of crowd control.
Also, totally personal opinion: Marnox is GOOD, but he is not that far above others that your strategy will be a walk in the park with him. Your strategy is wonky in itself, Marnox will make it just slightly less wonky.
As for Gorkas: I never used him, so I can honestly not give a decent opinion on him. I see lots of others use him, though, so I’m sure someone else can help you with that!
If you absolutely want to try a build with a summon that’s not Marnox, my personal suggestion would be Helgasercle, but then again, she’s my favourite and so I’m totally biased (but she also is the summon who keeps me alive way better than the “popular summons” Froster Lord and Templeshooter, who both very much suck in my eyes, but others like them a lot, so maybe listening to me isn’t the smartest thing anyway…)