Seeing as how the battle forums believe that there was a shift once: When did Classic Dr. Strange stop being Classic (and nearly omnipotent)?

When he stopped being the Sorcerer Supreme.

@ApatheticAvenger said:

When he stopped being the Sorcerer Supreme.

In the 80's when his writers were forced to start taking mandatory and regular drug tests. That being said in Battle forums you have about 90 percent of the posters who haven't read half the comics they talk about and in the search for objectivity in a medium that that is naturally inconsistent they read a few scans, respect feats and suddenly a character is reduced to a caricature. Its almost as if people forget that a lot of comic creators emphasis on the story rather than consistency of characters battle prowess. Just copy the lingo of everyone else around you though and being a sheep is as easy as Dr Strange after 3 beers.    

@Outside_85

Somewhere in the 80's is roughly where I'd call the death of Classic Strange.

I heard a couple reasons why he was weakened. I think Marvel wasn't happy with the sales for Dr. Strange comics, so they thoght it'd be smart to retool him into a more relate-able, weaker, standard sort of superhero character (just look how he went from looking sort of like Dracula, to looking more like Tony Stark, to eventually looking like a pretty-boy with a handlebar mustache in the 90's if you want evidence of his physical transformation). I also heard that, as turnover happened with Marvel staff, alot of the guys in charge didn't like the idea that Strange was strong enough to just show up and solve any problem in any big, comic-series spanning events...which they were planning to do (like SecretWars and, down the line, Infinity Gauntlet). Alot of people thought his strength undermined the impact of many of the events in comic's universe. And there haven't really been many worthwhile Dr. Strange comics since imo.

He was still a strong character even in his 90's comic series, but was still way weaker than his 60's to early-80's version.