Thorn Weed.

In the first room of the Long Library, you will encounter three Dhurons. These enemies take about three hits to defeat and have a charge attack. Dodge by moving away and then returning to attack.

Proceed to the next room, which has a path to the left and a path upwards to the right. Take the left path, which is a dead-end.

In the subsequent rooms, you will face Dhurons and flea men. Prioritize defeating the Dhuron closest to you first, taking them on one at a time.

At the end of the left dead-end path, you will find a Bronze cuirass, an armor upgrade.

Backtrack to the split path.

Take the path upwards and to the right. You will face several enemies, including Ectoplasm (pink brains) which can curse you, preventing weapon use. Uncurse items can be found in candles in this area.

After the Ectoplasm, you will encounter floating books that appear from the background when you approach. These can be avoided by continuing to walk.

After the spellbooks, take the path on the right and go up the stairs.

At the end of this path, you will obtain the FAERIE SCROLL relic, which reveals enemy names.

Return to the left path and continue left past the stairs leading down.

In the room to the left, you will find the Master Librarian, who acts as a shop.

Sell your Zircon gem. You should have approximately $2000.

Purchase the Jewel of Open for $500 (first item on the librarian's list).

Purchase the Castle map for $103 (near the bottom of the list). These two required items total $603.

If you have extra money, consider purchasing recommended items: Saber for $1500 (increases attack) or Leather Hat for $1000 (+1 defense, considered overpriced).

Potions or Library Cards are also options if you have extra funds. Library Cards allow teleportation back to the library from anywhere in the castle.

Items called “Magic Scroll X” add spell combinations to your spell menu. Once performed once, the input remains in the spell menu, making the scrolls a waste of money.

Once shopping is complete, you are finished with the Long Library and must backtrack to the Outer Wall.