Hirofortis has posted a thought-provoking thread on the EQ2 Forums regarding Critical Mitigation on raid gear and pondering just how much Crit Mit is needed to proceed in raiding. Just looking at the Tier 1, Tier 2, and Tier 3 raid gear available in-game, a player can acquire critical mitigation amounts of 110%, 127.8%, and 141% respectively, not including any critical mitigation achieved by having high numbers in the necessary stats.

Critical Mitigation from Raid Armor Sets

	T1	T2	T3
Head	10.00%	12.00%	15.00%
Chest	20.00%	20.00%	20.00%
Shoulders	10.00%	12.00%	15.00%
Forearms	5.00%	9.60%	12.00%
Hands	5.00%	9.60%	12.00%
Legs	20.00%	20.00%	20.00%
Feet	5.00%	9.60%	12.00%
Sum	75.00%	92.80%	106.00%
Max from Gear and Adorns	110.00%	127.80%	141.00%
Max with Gear and Stats	120.00%	137.80%	151.00%

Increase Critical Mitigation (Red Adornments)

Head	5%
Chest	5%
Gloves	5%
Boots	5%
Shoulders	5%
Bracers	5%
Leg	5%
Total Crit Mit	35%

Critical Mitigation from Intelligence/Agility

AGI/INT 500	5%
AGI/INT 1000	10%

Critical Mitigation is a measurement of how much your armor (plus a small amount of innate protection from Agility (for scouts/fighters) or Intelligence (for mages/priests) reduces the Critical damage abilities of the enemies you are fighting.

There is a lot of useful information in this thread already — it’s worth a read.