Tier

The Tier is the level of rarity/power an item has. Some items are not tiered, this is due to it either being: There are 21 Tiers. The best weapons in the game are Tier 21. The best rings in the game are Tier 10. The best armor in the game are Tier 15. The best Abilities in the game are Tier 10. Untiered items are not necessarily the best items in the game, they are just a kind of 'collectors' item. They are often traded for other collectible items, and are almost never used.
 * 1) Unobtainable
 * 2) Previously obtainable, but not now.
 * 3) Extremely rare items.