Is it possible to switch back to a previous difficulty

path-of-exile

I've just finished the first playthrough and unlocked the Cruel difficulty mode. Now I'd like to help a friend who is stuck at the final boss of act 3, Normal difficulty. Is it even possible ?
I can't find how, but it seems weird to me: how can I even trade with a player from another difficulty (without creating a new level 1 caracter) ?

Best Answer

When selecting a waypoint, you can change the difficulty by selecting an alternate difficulty displayed above the map waypoint list.

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In the picture, the difficult you are on is shown. Once you have completed Normal Difficulty, Cruel Difficulty will appear next to it.