theres only 2 way to grind it
locar and monster war.
consider that some player barely can join these wars/monster war, can make some other way to obtain it like by joining maze and boss give warpoints too, castle war etc. 1000 is alot for dual 5, i mean dual 5 shouldnt be that easy, but this aint easy anymore when u have collect plenty of item that are rare to get, and u have to get final stage 1000 war points to complete it, it gonna make like 8 months to dual 5, abit too long ( not mention those active player,but casually player)