You're going to have to re-phrase quite a bit of this question to get a better response. Ask Historians discourages counterfactuals.

However, the Chinese attack in Korea actually had two phases. The first phase, between late October and early November 1950, was a fairly small scale attack that only impacted some ROK units and one US regiment. The second phase launched in the last few days of November was the main offensive that rolled the US and UN forces below the 38th parallel. Between the two phases there was a two or three week gap and a PRC mission to the United Nations.

Many historians have theorized that the gap between the phases was designed by the PRC leadership as a space to allow negotiations. The US did not, in fact, use this gap to either negotiate with China or even prepare for the Chinese counter-offensive. They persisted in pushing forces up the Korean road network, ignoring reports of Chinese troop concentrations in the mountains and hills above the roads. Dysfunction in the US military, political, and intelligence systems meant that no meaningful steps were taken to avoid the crisis of December 1950, and there was a very definite window to avoid it by political or military action.

The sourcing on this is Russel Spurr's 1988 "Enter the Dragon" which is a very readable account (although it's journalistic and reads like a Tom Clancy book even though it's supposedly nonfiction) of how the Chinese counterattacked in Korea. There are more authoritative accounts, but I think if you that book you'd be able to write a better superhero story.