I don't think the creature spell lockout effect would be printable at any mana value, no matter how many safety valves you put on it (color intensive cost, high mana value, self-sweeping, leaving the battlefield "refund" and a way for it to leave the battlefield by itself)
I mean,
Portcullis is a card. This is a Portcullis that wraths YOU when it comes in and eventually self-disposes
Considering Portcullis is the only card with an effect like this, has no reprints, and has been a part of players' potential collections since before Odyssey block (which is the earliest block I'm aware of that took place before the multiverse was explored past Dominaria but also after other characters like Kamahl started getting more spotlight), I don't think printability is feasible.
Counterpoint, Portcullis is a card that's existed for ages and is relevant in no formats. My memory of Rath Cycle's time in Type 2 is hazy, but I'm not sure it ever was. Ditto
Lethal Vapors which has a lot of the same principle. Part of that is probably because you still get the ETBs of creatures that get locked up (on the first hit, and of course again on the second) but it still suggests to me that Bar is far from unprintable. True, it's been a hot minute since we've gotten
this exact sort of effect but oppressive cards like
Drannith Magistrate (well after Wizards began designing around Commander) and
Elesh Norn, Mother of Machines or
Jin-Gitaxias, Progress Tyrant are more recent. The Praetors in particular suggest to me that the big scary shutdown isn't all the dead.
I also want to gush about
Disciple of Caleus Nin but she's not really the same since there's no inherent forward-screwage there.