Purchase 2x Gold Voucher 500k and 8x Gold Voucher 100k from Nevaya's Buy Arcane Quills shop. If you're low on Gold, see the Gold guide. Trade the Gold Vouchers for 18 Arcane Quills. Then open the AC Get Spell Ink shop and buy 50 Entropic Ink. Use the leftover Quills to buy more Entropic Ink if you need it (they stack to 50).
Now enter /spellcraft. Press Begin and choose Entropic Ink to make this combination. Simply drag each matching symbol from the left into the corresponding slot. Repeat this until Rank 10.