A powerful but expensive horn with sprint build lol. Extremely powerful. Kind of outdated since Energy Mythic wouldn't go well with Full.mana but that mythic could be changed to other mythics like Fury for eg. Maybe Alchemy Mythic too but it's harder to use. However Alchemy is good with Primary skills.
Although Attack speed can help to compensate for Energy Mythic or Hunger Set.
Basic idea is that sprint is the main damage dealer and frozen explosions. It's not a new concept of course but this is one idea.
Advice for after you reached floor 200 and level 99: I'd suggest farm some packsize maps that you find easiest with some larimar or vendor bought map to earn gold and some chances of crystals as well as legends.
When you have full inventory of legends, salvage for dust which you can possibly use for crafting Legend items in Legendex. Unlocking is expensive but crafting it isn't hard.
Generally you could do ascension and choose fortunate perk but you'll have to be more prepared for that. Quest stones are a nice way to help.
A good ascension build is the Blightedswamp Build.
Although if you have crushing blow and defeat enemies quite well, work your way to floor 500 on any difficulty you like. This is for higher tier rarity crystals which will help you collect some for preparing your first farm builds and such. Also a nice way to find Elixir for 2+ All sets but in that time , you'd be wearing Nadroji jewellery or Haunting Amulet.
Eternalized Set and Crystalline Set items as well as mythical you can definitely aim for in terms of farm build. Then some Luck and Gold find in various means.
Make sure to save up for good luck.
Horn with 200% WD (used to be 100%) is Hunger Trap jaspered into Horn.
Recommended 3× 100% ED (ice DMG ) to go well with 200% WD and 5000 WD as well as 25% item quality.
Push the Limit 50% legend affix is found on certain legends but it's worth it because it will increase horn OH% by 50% which goes well with hero points for sprint.
Glasscannon/Barbarian for 50% DMG increase or a bit of both .Barbarian and push the Limit is only found but Glasscannon can be rolled from Ruby.
2-3× 100% Frostbiting or more which goes well with Frozen Set.
Set affix for DMG can be: Demonic, Frozen, Pathfinder/Defiant, Momentum/Adventurer .
Sprint with momentum makes sense since it's a move speed build.
For high floor wreckage, also have some dodge and block % if you want for better survival and dodge goes well with Pathfinder set.
Everything else you can find out.