Corrupting is an end-game enchant system by modifying an enchanted item into corruption. Corruption ignores Random Item Options listed in each equipment and are capable of granting any types of addons into a piece of equipment, and allowing any duplicate addons such as ATK% or MATK% to be able to coexist more than once in a single piece of equipment.
Once an equipment changes into corruption, the only way to revert it back is to use Purification Gem, deleting corruption and every addons inside it.
Corrupting and Greater Corrupting gem works by rolling a failure/success then overwrites addons if they're a successful roll. By default, Corrupting gem rolls only ONCE, Greater corrupting gem rolls TWICE, below is rough diagram on how the gem works
The gem rolls every individual addons and has two outcome, success, which returns in a random modification, a failure keeps the original addon, including empty slots.
Extra notes about corrupting gem facts
-It has 65% chance to max roll an enchantment, 35% to minimum roll on range [check the equipment appraiser]
-Greater Corrupting Gem has 7.14% chance of doing nothing, the normal one has 14.28% chance.
-Quality can drop to whopping 50%, but can increase it up to 20%
-The quality is more likely to stay the same
-The exclusive addons are; All Skill +1, Skill Radius +1, Recover AP by 2 per actions (not affected by 2hand mod or enchant grade)
Corrupting gem has a higher chance to not roll, which means higher chance for some addons to stay, this is a very important information as you can corrupt a good item and hope for the bad enchantment to get rerolled instead.
Greater Corruption gem instead, have higher chance to roll corruption enchants, so they are better for items that has few or no good enchantments, as you can expect most of them rerolled
Tips to farm Corrupting Gem
Mystic Blue and Purple boxes no longer drop individual gems and instead have a chance to drop bags of gems. These boxes drop from events and killing rift MVPS, and doing Raids.
Clearing rifts rewards you with rift charges, 1138 rift charges are equal to one Corrupting Gem
Killing monsters will eventually yields rarer gem, below are the table for monster drops.
Higher level Raid rewards bigger bag of gems.
Clearing high level spire are your primary source of corrupting gems