The Vault

1. A spell will help you identify the correct cube. But you only have three spells (maximum) to do it. Then the alarm fairy and the guards show up.
2. The spell isn't BLORPLE, it's JINDAK!
3. JINDAK when you first enter the room. You'll notice something unusual about the two piles.
4. The "real cube" doesn't glow at the same intensity as the fake cubes. But...
5. ...it could be brighter OR dimmer.
6. You have enough time for only two more JINDAKs (three in all) before you have to grab the correct cube and BLORPLE it out of here.
7. This is a variation of a classic coin-weighing puzzle.
8. To get the correct cube from the Outer Vault, enter the Outer Vault without the treasure. Have all your items in the zipper so you can easily move cubes around. Have JINDAK memorized thrice and BLORPLE memorized once. Develop clue 9 and follow the directions.
9. The first JINDAK should be done with four cubes on each pile. TAKE X1, X2, X7, X8. JINDAK. (X3, X4, X5, X6 on the first pile. X9, X10, X11, X12 on the second pile.) If the piles are even then develop clue 10. If the piles are uneven, notice which pile is brighter, then develop clue 13.
10. TAKE X3, X4. PUT X1, X2 IN THE FIRST PILE. JINDAK. (X1, X2, X5, X6 on the first pile. The second pile remains the same.) If the piles are even then develop clue 11. If the piles are uneven, then develop clue 12.