Legends Gold Premium 

Doubles [X2] the EXP/SP from any mob for 3 hours per day for 28 days and enables you the following buffs and options : 

 Physical Damage 10% Absorption
 Magical Damage 10% Absorption
 Physical Damage 10% Increase
 Magical Damage 10% Increase
 Attack Rate 10% Increase
 Parry Rate 10% Increase
 Alchemy Probability 10% Increase
 Lucky 5% Increase
 STR 10 Increase
 INT 10 Increase

5x Instant Return Scroll
3x Resurrection Scroll
5x Reverse Scroll 

Purification Seed - Premium Quest rewards : 

100 Purification Seeds = 6000 SP 
200 Purification Seeds = 14000 SP 
300 Purification Seeds = 24000 SP 
400 Purification Seeds = 32000 SP 
500 Purification Seeds = 50000 SP

We basically upgraded the original Premium to the Legends Gold Premium for you by giving extra value to the quest reward for the same price of 300 Silk in the Item Mall.  

Also don't forget that this quest is x3 times repeatable which means the potential is to get 150K SP there monthly.