Stats Guide - Crit Stats

Crit Rate (or simply "crit-CRIT", "crit%" or even "cr-cr%") is a stat that increases your chance to land critical hits to enemies,
which are represented by yellow damage numbers above their head.

Every class has a 1% crit rate value by default; the Crit Rate can be countered by the Crit Resist.: each 1% percent of crit resist. the enemy has will subtract 1% of your effective crit rate.

At the moment, the crit rate soft cap to land theoretically 100% of your hits as critical hits is 80% for a specific amount of accuracy required depending on the dungeon you are clearing; this exists since PvE enemies don't have any crit resist. at all yet*.

Note*

After some tests**, it is verified that having 100+% crit rate grants you the security that all your normal hits become crit hits. However, it doesn't prevent your hits from being missed if you lack accuracy!
Therefore, if you absolutely want that 100% of your hits are crit hits, you must reach the minimum accuracy value for 0% miss in the concerned mazes (check the link above).

Note**

Crit DMG (or "cdmg") are a damage "multiplier" added to your attack stat when landing crit hits.
The basic value of cdmg is equal to your Min. ATK value, thus making a crit hit about at least 2x stronger than a regular hit

Having more than the Min. ATK value as Crit DMG will result in dealing more than twice your normal damage. They can be increased through gear sub-stats, A.R Cards, titles, brooches, etc.
An Attack gain will also result in getting some cdmg, for which the amount added will correspond to the gain of min. ATK (so 80% of the global gain). For example: adding 1000 ATK will add 1000 max. ATK, so that will result in 800 min. ATK, so you end up with 800 more cdmg.

Critical Hit DMG calculation formula here

In case of a choice to make between stats to add, the Crit DMG stat loses strength among other multipliers in terms of long-term fights.