
Let me see if I understood.
Is your Wizard fighting the Demigod build?
You are simply ignoring the Demigod's defenses and tatics.
1) Let's recap.
You are fighting a highly efficient creature in disguise and you cannot know who the real caster is.
We dealt with this -- he's either in his little hidey hole, and so not even a problem, or he's out. If he's out, then we can scry the group and figure out who the leader is -- he's the one giving orders, the one we can't scry, and one of the two winged creatures.
2) He is surrounded by powerful minions that simply kill any Wizard instantly.
With a general command (He doesn't have to be giving command all the time).
"Protect me with your best abilities and defeat any creatures other than us."
Even if the Sorcerer is knocked out, his command remains.
Yes, accounted for. He has 60 Magen, which leave the Sorcerer with a base of 2 hp, buffed with spells and the Leadership feat. He also has his simulacrum, who doesn't have a 9th level spell slot. He also has the DMM -- which is a heck of a lot of cheese, because it's not the character that does this himself, but whatever, accounted for.
He does, however, only have 1 summoned celestial -- the Simulacrum cannot maintain one without burning through his spell slots -- the lack of the 9th level slot for planar binding is the problem -- best the Sim can do is manage 180 days before starting to have to cycle slots, which they run out of pretty quickly.
3) And all of your minions have long range, fly and can instantly kill a Wizard 660ft.
Which is why the wizard didn't approach from range.
4) Do not think that you will simply approach and cast a spell, without first explaining in detail how you will approach, recognize the target and not be killed right away.
Easy, we know it's one of the two winged medium creatures. The approach is as follows -- the Simulacrum teleports both the Wizard and the Sim to the location, both invisible (concetration by the Sim) and flying (concentration by the Wizard). They appear at exactly 120' from one of the winged medium creatures, with surprise, and the Sim casts a 9th level dispel magic on the target. 50/50 chance. If the target doesn't disappear in a puff of snow, it the sorcerer. If it does puff. the wizard teleports out. Recasts Sim next day. Waits until the Sim reappears in the scrying, and then scrys the sorcerer because they don't have Mind Blank (having used Wish to recast Simulacrum). Attacks again, this time with precise targeting.
If the sorcerer is hit with the dispel the first time, or one the second run, the Wizard casts any damaging spell that deals 26 hitpoints or more -- you can pick it. Sorcerer is dead. Wizard cannot escape counterstrike, if one exists, from the remaining minions, but that's okay, the Wizard has a Clone.
5) Everything seems very easy with all the spells, feats, races and subclasses available, assemble a complete build and you will see that it will lose 80% of its theoretical power.
You can pick the subclass -- doesn't matter. You can pick the spells, so long as I have the ones detailed above -- they don't matter. The Sorcerer is powerful, yes, but only because of his minions, which are his Achilles heel due to the loss of hitpoints. The needed buffs to counter this are the focus of this attack -- dispel the buffs and the sorcerer is very weak.
"Sure he does! The sorcerer has been dispelled, so it's easy to pick him out. Wizard summons, say "kill that one," and it's done."
Read 1, 2, 3 and 5.
No, you can't cast dispel him.
Did, though. Wizard is pretty smart.
"Well, no, we're at 120'. I mean you quoted where all this happened and asked how I'd get tgrpugh your 26 hitpoints, remember? I messed up and went with the 56 from Aid, so, yeah, could have used a 9th level magic missle. I firget, do ypu know Shield? Ah, probably best to stick with the irnoy. Or... use Horrid Wilting. Man, what a service! Your Sorcerer just rehabilitated Hirrid Wilting!"
No, you are not at 120ft.
You are dead long before you get it. Read all numbers.
We teleported there, so... I mean, pay a little bit of attention?
"Well, not really. They're uncommanded since your dearh, so they dodge and use they're move to avoid danger.
Oh, who killed him?
Dude, ypu got dispelled -- you don't have any of that! Again, you've already quoted this part and asked what happens next, so ot's a little late to be reneging on this. Maybe, if I might be so bold, you should read things more carefully?
Which we? The Sorcerer died, so the Celestials are off the hook. You've got to be more specific, man."
Nothing about It Works.
And you haven't given a single reason why. I expect that the general thrust of this response is something like "but he's in his fortress!" which is lame. Stay there -- this character is utterly unimportant if he's in his little fort (which has been detailed how that gets destroyed, but I think your last bit was demiplane, which is also losing).
"You wished... with what spell slot?!"
You wished for the celestial, not the sorcerer.
Weird, you said, "I wished...." So, very confusing.
The celestial cannot reach the sorcerer by numbers 1 to 4. And even if it were, it would be useless. Sanctuary spell blocks any potential efficient attacks.
The celestial was summoned at 120'. As for Sanctuary -- you didn't cast it, because it's not on the list of things you cast that you just provided. Also, even if you did, it's been dispelled.
If you do not complete your build, you will have no answer for obvious reasons.
So far, you haven't come up with anything that actually answers the sketch I've provided -- I don't need a full build because nothing I'm doing relies on any subclass abilities, or on a complete spell list. It's very simple -- it goes directly for your weaknesses, and leverages the fact that the Wizard can cast Sim way more often than you can, and has a Clone, so can engage in whittling you down. Heck, even if we don't scry, I just send the Sim in on a suicide run with teleport, invisibility, and dispel magic -- this destroys a minion every single time without having to be good at targeting. If it hits you, the wizard can see this via the scrying on the Sim he sent, and leap into action with his alpha against your 26 hitpoint and no spells.
Your entire build relies on the minions, which are fragile and subject to destruction, and you cannot rebuild them fast enough (or at all, with regard to the Magen). And your sorcerer completely lacks the ability to actually counterattack the wizard in any way except hoping the wizard comes back to them. You're entirely on the defensive -- the Wizard has the initiative and can dictate the pace of the engagement, which, given you MUST win in one fell swoop because you cannot withstand a protracted attrition fight, means you will lose.