The Infinity runeword in Diablo 2: Resurrected is ‘BerMalBerIst’. So, to make an Infinity polearm, you need to add a Ber rune, a Mal rune, another Ber rune, and an Ist rune, in that order, to a 4-socket polearm. Remember, they must be added in exactly that order, otherwise the runeword will not work.
You won’t find a 4-socket polearm anywhere on Normal difficulty (except maybe the Secret Cow Level), and any normal polearm found on Normal difficulty won’t get as many as four sockets if you add
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