New chapter out
Past this is spoilers of the chapter.
So how best to use the simulacrum spell? For combat, I think having minions controlled remotely by the real Zorian follow the fake Zorian who casts actual combat magic. Reduces risk to real Zorian, and gives him the attention to micromanage his golems/whatever minions he chooses.
(The simulacrum also allows him to make more golems. Making the animation core was said to be the most demanding part, and now he has two people who can do it to his specifications)
When Zach gets good enough at soul awareness to learn the simulacrum, for combat I think he'll get less comparative use out of it. Maybe have one focus solely on defense while the other rains down the fire? Even with his mana shared between two people, he still has a huge mana reserve, so he won't need to have one copy be the only one using mana intensive spells. Taking some lessons from Xvim could be a good idea, as Zach doesn't seem to have focused all that much on specialized defensive spells.
For non-combat, Zorian will be getting vastly more use out of the simulacrum spell than Zach. The author said on his patreon page that simulacrum don't integrate their memories to the original when they end or anything that convenient. Zorian can get around this most of the time with memory packets and telepathic memory sharing. Anything the simulacrum learns could be shared extremely easily, especially as Zorian made those discs that relay telepathic messaging a while back. Now he can take paths that he previously wouldn't because they were too dangerous, like exploring deep in caves or going after necromancers/other people with soul magic.
For a story titled Mother of LEARNING, this is a pretty big boost to Dorian's power set.