1) Bastion is hidden and cast subtle invisibility. (Nondetection blocks See Invisible and True Seeming Spell).
2)He remains totally undetectable.
3) He uses Trance of Order.
4) When approaching a melee hit range, he cast Subtle Wish for Antimagic Field.
5) Now, your minimum attack is +19 to hit (Clockwork's Trance of Order), which automatically hits any Wizard. With sentinel feat (I traded + 2dex for sentinel feat).
It has at least +18 to concentration checks to avoid lose his concentration.
6) Your Simulacrum's assassin makes a deadly attack each turn. It's a lot of damage.
Wow, an actual strategy? Now if you could post a complete build so we can double-check it, we'll be able to start discussing it.
The way it resolves, using D&D rules and the strange restriction you put on the thread...)
1. You are hidden (why not... despite it being forbidden according to your rules, since it requires DM's fiat)
2. You cast Trance of Order... which doesn't influence your bonus to hit, it prevents you from rolling low. This isn't the same thing, even if in this case it doesn't change a lot of things compared to a Wizard's typical AC).
3. Your intent is to cast AMF and approach into melee range. Initiative is rolled. On your action count, you Wish for an AMF. You're no longer benefitting from Greater Invisibility and Nondetection, and Trance of Order. If you're forgetful with positionning, your various Simulacra might be suppressed as well so be careful. Franckly, at this point, you'd better off sending an NPC Assassin with the Sentinel feat alone as you won't contribute anything meaningful to the fight.
4. Provided he's still within range of your Sentinel feat at his turn, the target can't move away if you succeed on an AoO using your reaction (which would get a reasonable chance to succeed depending on the Wizard's AC but not be guaranteed either), you can reduce his speed to 0 for this turn, which would prevent a use of a Dash action (since it gives another move but the move speed would still be 0 ft.)
5. This resolves as whether your Assassin's simulacrum can kill the wizard before the Wizard's Assassin simulacrum can down the agressor. The result will certainly only demonstrate the superiority of the Assassin Rogue over spellcasters in non-magical combat and the result comes from the luck of the dice as both casters are comparable in terms of durability.
7) While the Wizard is within the antimagic field, he cannot escape, since sentinel feat, It will prevent you from trying to escape and Bastion's constant attacks will surely be a painful death.
Within the field of antimagic, The Bastion is easily healed with his Clockwork Cavalcade and his Simulacrum's Clockwork Cavalcade.
You cast Antimagic field. Summoned spirits of orders by clockwork cavalcade can't manifest or heal anything. Have you forgotten the beginning of your sentence?
The Bastion will murder your target painfully, with deadly perforations in your body.
Bastion can heal 200 hp per turn.
This makes it a true survival machine.
Unless someone cast Antimagic Field at the beginning of the fight, of course.
Bastion's Simulacrum Sorcerer remains hidden to defeat any approaching enemy and will heal Bastion with Clockwork Cavalcade for sweet 100 healing, over and over.
Wondering why it doesn't work, over and over.