Just look here in forum to find some build sets with high lucks for farming.. if your looking for ring I guess you have bad luck for not finding 1 try to look at Store or kill bosses.
Kill Cartographer in floor 200 or buy from store. Then use it and kill the Cartographer to drop level 201 Map..so on and so fort.
Then start your adventure of farming legends.
Tip : Get the Ascension who gives you more gold by selling Gears/Items. Pardon me I forgot the name of it. (as always I forgot).