The Duel Map is the map equivalent of the duel mode. You start with lvl 1 hero and week 6 army strength, level up via sphinx, buy artifacts, learn spells, upgrade and you're ready for battle! The map is based on 3.1 but has a number of improvements on many areas so it has its own balance and meta.
I have been submitting gameplay/faction articles for the past week or so, ModDB is a handy site.
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H5 is still alive and kicking, join us in the Duel Map discord server!
Map also hosted on Moddb