Drop-restricted item
Drop-restricted items are items that cannot randomly drop anywhere from monsters or chests.
This can include:
- Quest items and rewards.
- Items that can only be created through crafting or indirectly through other items, such as gems.
- Items that can only be dropped by a specific monster or object.
Drop-restricted unique items cannot be obtained from gambling or an 
Orb of ChanceOrb of ChanceStack Size: 10Unpredictable either upgrades a Normal item to Unique rarity or destroys itRight click this item then left click a normal item to apply it.
.
Legacy items
Legacy items (also called legacy variants) are versions of items that are no longer obtainable due to a result of updates or balance changes. Typically they can only be obtained by trading in permanent leagues, or less commonly in temporary leagues due to mid-league changes.
Modifiers with only numeric range changes are usually able to be rerolled using a 
Divine OrbDivine OrbStack Size: 10Randomises the numeric values of modifiers on an itemRight click this item then left click an item to apply it.
Shift click to unstack.
(or the reroll modifier value corruption outcome) to their new value or range.
Modifiers that were added or removed (unless they were simply hidden by setting the numeric value to 0) cannot be added or removed using a Divine Orb, unless otherwise specified. In some cases, this can result in "semi-legacy" items which can have a mix of current and legacy modifiers.
Drop disabled
A drop disabled item cannot drop at all. This may be due to special item rules, the item's acquisition methods being removed from the game, or the item not being officially released. Drop-disabled items are typically finite in availability or not currently obtainable. Most drop-disabled items that do exist in-game can be traded.