This is a questline to get x 5 mass of  pure magic every week . 

to start the quest you need to be lvl 60 , go to  o'draxxia and take the quest (Essence of Tunta) Celphie's Special Alchemy  from Celphie .

Now you need to give Celphie 

x 10 dark spirit's Geed, you can get it from defeating Dark rift.
x 100 fire Horn, you can get fire horn by gathering , random drop from (wild) animals by butchering or tanning them . ( or you can buy it from the central market ).
x 5 Latent Aura of your choice, you can get the Latent Aura by defeating bosses.

Next talk to celphie and take the quest (essence of tunta) Verti's Assistant and go to the Queen of O'dyllita to finish the quest ( Viorencia Odore).

Now you can start the weekly quest ( Delivering Essence of Tunta )  .

you need to Hand over essence of tunta 

 to make the essence of tunta you need Alchemy tool .

x50 Fruit of Enchantment, you can obtain the fruit of enchantment by gathering or farming ( or you can buy it from the central market )

x50 Refined Delotia Reagent, you can craft  it (check Crafting note for more info) or buy it from central market . 

x10 Black Gem Fragement, you can get the black gem fragment by gathering  ( or you can buy it from the central market ).

x50 Fine Lightweight Plume, you have the option to  buy it from Central Market or NPC  ( 'Lavientia Batian' in calpheon )  or processing .

x2 Latent aura of any boss .

Now go back to Celphie and give the essence of tunta to finish the quest .