Thanks to the introduction of ultras this class' farm has significantly reduced in time, people can no life this and finish in 3 days or 1-2 weeks depending on when you started. The 3 days feat is only possible where you started farming on a thursday, doing Ultra Dage on reset also.

At the bare minimum you are required a Dark Caster class in your inventory to access this location and Rank 10, check Faction Reputation Guides for this. It is recommended to be level 80 so you can participate in the Ultra but be a masochist if you will. By completing the Ultra you get Dage insignias which can be used for the merge shop to craft LR materials, though bare minimum requirement is that each Fealty 1, 2 and 3 are completed atleast once so you may complete Fealty 4.

Revenant Spellscroll

Conquest Wreath

Exalted Crown

And that is pretty much the bare minimum required, from this point onwards you can choose how many weeks you wish to do Ultra Dage for insignias and skip the farms. You can speed it up by farming obviously but it is upto you.

From this point onwards if you choose not to farm anymore towards LR and only focus on the weekly quests provided by Ultra Dage you will spend:

A total of 31 insignias requiring 7 weeks of Ultra Dage. Alternatively if you farmed Fealty 2 twice you can do this in 6 weeks of the ultra.

A more active method of farming for LR is doing 2 weeks of Ultra Dage and farming the rest. This will be how you spend your insignias: