These cards are either too weak or too difficult to slot in the archetype. It is possible some of these cards can find a home in the future.
Rule of Law/Arcane Laboratory/Eidolon of Rhetoric- Decent control cards. The ROL effect stops a lot of combos and lends itself well to Draw-Go. The issue is building around them. MAN looks to take advantage of the CA engines. ROL restricts the benefit and makes it more difficult to combo under.
Containment Priest- A worse Graffdigger's Cage. Flash can be a nice "Gotcha". As it stands, the priest is too narrow and easy to answer. Makes it more difficult to play with symmetrical wipes too.
Kataki, War's Wage- A Tabernacle for artifacts. Being on a body is nice for Tymna. But, it is weak vs removal and wipes. Also hinders current MAN builds.
Chains of Mephistopheles- Does a good job of shutting down opponent's CA engines, as well as most Scepter lines. Breaking Parity is tough though and some decks remain largely unaffected.
Kambal, Consul of Allocation- Can fulfill the same role as Damping Sphere. The cmc is awkward to slap down on turn 1 or 2 and he doesn't outright stop storm. Kambal is asymmetrical and ramps up Ad Naus though.
Spirit of the Labyrinth- See Chains
Alms Collector- A much worse version of Notion Thief. Does not stop Scepter lines and Storm can actually power through it. Still decent with wheels and makes Doomsday more difficult.
Fate Unraveler- Can be a fast clock in some respects. The problem is, Scepter lines can draw just enough cards to answer and then continue to win. 4 mana is quite a bit too.
Null Rod- Great hoser against many decks. Problem is that MAN hasn't got a good way of fighting through it.