The levels from 70 to 75 can be obtained by farming Lustrous wisps west from The Slayer tower. After you've finished, create another Boon using 1375 Lustrous Energy. Then, move to the next location with OSRS Accounts in case you don't have a means to reach Elder's Hall. You should continue working on Lustrous wisps until reaching 80. To get to the Elder wisp's farming zone you'll need to use...