How to become an Archmage?

I didnt found any hint in 5th Edition.
From 3rd Edition I just remember: a Magus have to challenge an Archmage, the Archmage sets a contest. If the magus win, he get the title, the old archmage loose it ... which would lead to lesser and lesser archmages in the order and to they question: how they first archmages became archmages?

How does that work in 5th Edition?

Archmages in 5e are described in Guardians of the Forest p24.

To summarise, to become an Archmage you need to invent a spell of 7th+ magnitude, be famous for some great deed, and win a challenge against an existing Archmage. Each existing Archmage can grant the title to at most seven challengers.

txs :slight_smile: