How treasure chests work: the difference between a chest and a box, where the keys come from, and what drops and is spoiled from the chests of every level, from 21 to 84, with the grade of the enchant scrolls inside.
The keys are needed to open the Treasure Chests, from which armor and weapon enchant scrolls are extracted. It is a thankless business, and it becomes more so as the level rises. While from small chests you can get a dozen D weapon scrolls in an hour, at high levels you can run about all day and not extract a single S weapon scroll. So it is for you to decide whether to take it up or not. But in any case, even when levelling on mobs and running past a chest, you can and should open it; the main thing is to have keys of the corresponding grade.
The chests are chests and boxes, but they cannot be told apart by looks; a patch for chests is needed. Chests are ordinary mobs with drop and spoil: when a key is used on them, the key disappears and the chest aggroes on you. Boxes, when a key is used on them, may either disappear (you will hear the corresponding sound) or open. On opening there is a chance that you get an armor or weapon scroll. If you hit a box, it explodes with an area fire attack. Because of all this a patch is simply necessary, so as not to waste keys.
The main generators of keys are the dagger classes, which have the skill 
Summon Treasure Key. You can put such a character on a macro (or a whole heap of them on different windows), and they will produce so many keys for you that you will get tired of opening chests with them. Keys also drop from some mobs with rather good chances, so they can be knocked out too. The spoil of keys from mobs exists only in the Rift.
- The keys:
Deluxe Chest Key - Grade 2, Deluxe Chest Key - Grade 3, Deluxe Chest Key - Grade 4, Deluxe Chest Key - Grade 5, Deluxe Chest Key - Grade 6, Deluxe Chest Key - Grade 7 and Deluxe Chest Key - Grade 8; on the page of each key there is the list of monsters it drops from. Keys of the first grade are absent from the game: I had such keys a couple of times, but that was a bug of the server admins.
What is inside the chests
In general the Koreans show a wish to structure the drop from chests clearly: you will see neither weapons nor jewelry in it. Only helmets, shields, gloves and boots. And they tried to do it this way: if a chest drops gloves and boots, the next one by level will have helmets and shields of the same grade and tier (low or top). In principle they almost managed it: the failure happened at the chests of levels 72 and 75. They simply had two left unused by their own algorithm, so into these chests they had to stuff low A-grade gloves, boots, and helmets with a shield a second time. And one more failure happened in the strict chest hierarchy: the drop chance of enchant scrolls from the level 54 chest is much higher than from the level 57 one.
- Treasure Chest level 21. From boxes, D-grade armor and weapon scrolls; from chests, top no-grade shop gloves and boots; in the spoil, starting resources. Level 24. From boxes, D-grade scrolls; from chests, a top no-grade shop helmet and shield; nothing interesting in the spoil. Level 27. From boxes, D-grade scrolls; from chests, low (quite low) D shop gloves and boots; in the spoil, starting resources. Level 30. From boxes, D-grade scrolls; from chests, a D shop helmet and shield; in the spoil, ordinary healing potions. Level 33. From boxes, D-grade scrolls; from chests, D-grade gloves and boots that can be neither bought in a shop nor crafted; nothing interesting in the spoil. Level 36. From boxes, D-grade scrolls; from chests, a D shop helmet and shield; in the spoil, steel. Level 39. From boxes, D-grade scrolls; from chests, D-grade gloves and boots needed for many sets; in the spoil, recipes for top D jewelry.
- Treasure Chest level 42. From boxes, C-grade armor and weapon scrolls; from chests, a top D helmet and shield; in the spoil, key materials for top D jewelry and starting resources. Level 45. From boxes, C-grade scrolls; from chests, C-grade gloves and boots needed for many sets; in the spoil, Mammon dyes +1 -1. Level 48. From boxes, C-grade scrolls; from chests, good C-grade shields and a helmet; in the spoil, key materials for crafting the Plate Leather Set. Level 51. From boxes, C-grade scrolls; from chests, C-grade shop gloves and boots; in the spoil, the resource Braided Hemp and Mammon dyes +3 -3.
- Treasure Chest level 54. From boxes, B-grade armor and weapon scrolls; from chests, a top C helmet and shield; nothing interesting in the spoil. Level 57. From boxes, B-grade scrolls; from chests, low B-grade gloves and boots; in the spoil, a B weapon scroll and the recipe for top B jewelry. Level 60. From boxes, B-grade scrolls; from chests, low B-grade helmets and shields; in the spoil, starting resources and Mammon dyes +4 -4. Level 63. From boxes, B-grade scrolls; from chests, top B-grade gloves and boots; in the spoil, key materials for top B jewelry.
- Treasure Chest level 66. From boxes, A-grade armor and weapon scrolls; from chests, top B-grade helmets and shields; in the spoil, key materials for top B jewelry and Durable Metal Plate. Level 69. From boxes, A-grade scrolls; from chests, low A-grade gloves and boots; in the spoil, the needed resource Oriharukon Ore. Level 72. From boxes, A-grade scrolls; from chests, low A-grade helmets and a shield; nothing interesting in the spoil.
- Treasure Chest level 75. From boxes, S-grade armor and weapon scrolls; from chests, again low A-grade gloves and boots; in the spoil, Stones of Purity and the blue mold. Level 78. From boxes, S-grade scrolls; from chests, again low A-grade helmets and a shield; in the spoil, the recipe for S soulshots. Level 81. From boxes, S-grade scrolls; from chests, top A-grade gloves and boots; in the spoil, the red and the blue mold. Level 84. From boxes, S-grade scrolls; from chests, top A-grade helmets and a shield; in the spoil, key materials for crafting S weapons.