Crystar was another toy-based comic. Marvel put some talented folks to work trying to make it into another hit like Micronauts, but it didn’t really work.
These issues are almost definitely not canon–however some of the characters returned 30 years later in a 2015 Weirdworld comic (and then in a few most stories thereafter).
I’m not going to get into the Crystar-world stories in the 11 issues because they really don’t matter and I”m not sure they’re canon. But there were ties to the 616.
In issue #3, Doctor Strange guest starred. Crystar, the wizard Kalibar, and Crystar’s gal Ika are teleported into Strange’s home by accident. They mostly just talk together until they figure out how to get home.
It’s actually a solid story. Mary Jo Duffy was a really good writer.