Deciding factors for an upcoming featured 5* arena?

Every 2 weeks, there is a non-new (existing but not a brand new) champion introduced to arena. What are the factors involved in champion selection?
Because we have seen Antman 3 times, Domino, Cap IW or even Medusa more than once but some really older champions like Hood or Guillotine only once on release
Because we have seen Antman 3 times, Domino, Cap IW or even Medusa more than once but some really older champions like Hood or Guillotine only once on release
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And if I recall correctly, they re-ran the Antman twice within July 2018 because of some problems (outage/maintenance ?) that first week. So you can’t really count that as an additional time he’s been in arena.
But correct in asking about Hood, he might have been skipped as a 2nd time around Hero maybe because of other end-of-year or other specialty arenas when otherwise he might have come up.