Master Order and Lord Chaos are cosmic abstracts within the Marvel cosmological hierarchy. They are said to personify their own representations and must co-exist to preserve balance in the universe.
Quotes from Al Ewing
“In the past, they’ve been a fairly stable pair; one of the things I liked about Marvel’s interpretation of these forces was that they were a team, rather than enemies, Without Order, the universe couldn’t have formed, because it’d just be a roiling sea of endlessly mutating physics; without Chaos, it also couldn’t have formed, as the random spark of change wouldn’t have brought it into being in the first place. Having these fundamentals fight—and especially asking the reader to pick one or the other as ‘the goodie,’ depending on the mores of the time—feels silly.”
“If the balance between them fluctuates, things [can] go bad very fast, in the same way that the balance of human forces in our own world could tip into chaos—or a merciless, punitive order—very quickly.”
Master Order and Lord Chaos are ranked below the likes of Eternity and Infinity but above the likes of Galactus, In-Betweener, Stranger, Zeus, Odin and Celestial One Above All.
Master Order and Lord Chaos can see the future. This shouldn't be a surprise as they are abstracts.
Master Order and Lord Chaos are responsible for the creation of another abstract by the name of In-Betweener who maintains universal balance. For more details on In-Betweener here's a respect thread for him credit to @professorrespect
Defeating Living Tribunal
Honestly this makes no sense whatsoever but it did happen. Both Master Order and Lord Chaos overthrew and defeated the Living Tribunal together though to be fair this happened after the restart of the new Marvel Multiverse so power levels may be different.
Master Order and Lord Chaos can fuse together along with In-Betweener to became a completely new cosmic entity known as Logos.
Master Order and Lord Chaos honestly don't have that many feats or appearances for that matter and tends to rely mostly on scaling to determine their power levels. There is also a single showing of them getting beaten by Lifebringer Galactus and while a big deal was made about it, it simply isn't a feat at all that favors them. We do know they are abstracts responsible for creating another abstract. Overall they are at least universal in power and potentially multiversal though that would come down to interpretation.