Critical hit chance allows hero to deal double damage with physical attacks (crit. chance does not affect magical and pure damage types).
There is a formula to calculate the exact percentage of dealing critical hit:
Hero’s Crit. hit chance/(Hero’s crit. hit chance + opponent’’s main stat)*100%
For instance, Ishmael with Crit. hit chance of 7182 attacks Astaroth with Strength (his main stat) of 13030
7182/(7182+13010)*100 = 55% that Ishmael attack would deal double damage.
Dodge allows to completely ignore physical damage (you can’t dodge magic damage in Dominion, however).
Dodge uses the same formula as crit. chance:
Hero’s dodge ratings/(Hero’s dodge+opponent’s main stat)*100%
Let’s take Elmir with dodge stat of 6350 who's getting hit by Astaroth with Strength (his main stat) of 13030
6350/(6350+13030)*100 = 32% that Elmir will dodge Astaroth's attack
You can read more about Hero’s stats >>here<<