Both your sentences are incorrect. This is one possibility: She will wait in the cold underground as the worlds descend into chaos. Check that you do really mean "worlds" and not "world".
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Anonymous- Is 'she will be waiting-' incorrect too?"she will be waiting" is also correct.
Anonymous- What do you mean that check the words between "worlds" and "world"?In your sentence, one might expect "world", singular, meaning the planet that we live on.