Yes. Farming for legends and gold. Gold for ascension reasons and in general to save up. Legend farming will be more important now because level 100 items salvaged for dust is 5 dust each. It takes 200 dust to unlock most items .
Although if you can give this a try, you can go all the way up to floor 500 from floor 200 on very easy mode or any other difficulty you're comfortable with. Getting there will help in increasing tier rarity for crystals and mythstones collection which will help you be prepared for ascension build and farming build at the same time. Or until you have 6 quest stones for ascension.
Mythic 3 floor 250 isn't too difficult and different from floor 200 in mythic 3 but you can already start getting Crushing Flames legends and even Sadism . Both can be obtained by amethyst but those legends have.It's best to be prepared though. Fire dmg % (ED%) on staff for example.
Floor 350 is for legends with Mythical set affix but this can be gotten at any difficulty, including very easy mode. Will help a lot finding ultra rare mythstones for high floors with increased Tier Rarity and a free mythic.
Mythic 3 floor 350 is also when you get those Crystalline and Eternalized legends for farming but that is if you can handle floor 350 mythic 3 and 400 for CV (Cerebral Vortex) legends which are good for PvP.
Lastly floor 400 has Aether legends which can be gotten on very easy or any difficulty for that matter. The chest and hat have 100% ED which is a valuable affix.
Although in any case, you can also farm floor 200 for a while and unlock the legends you need, that being the Eternalized and Crystalline for farming. Dust from salvaged legends ftw.