A normal crit is 1.5x and with shadow the damage is 1.6x. Lets say you do 100damage each attack and you have 50% crit with thief and 45% with shadow stone. For each test you make 100 identical attacks.
Thief at 50% crit chance, 1.5x modifier
50crits at 150damage = 7500damage
50 non crits at 100 damage =5000damage
Total 12,500damage after 100 attacks.
Shadow at 45% crit chance 1.6x modifier
45crits at 160 damage = 7200 damage
55 non crits at 100 damage = 5500 damage
Total 12,700damage after 100 attacks.
So at 45% crit Shadow is better.
Now at 30 and 25% crit.
Thief at 30% crit chance 1.5x modifier
30crits at 150damage = 4500
70 non crits at 100 damage = 7000
Total 11,500 damage
Shadow at 25% crit chance 1.6x modifier
25crits at 160 damage = 4000
75 non crits at 100 damage = 7500
Total 11,500 damage
So at 25% crit adding shadow or thief would net the same damage
At 26% crit shadow starts to pull ahead. So with no mundus stones on, if you are at 25% crit you will get the same damage if you equip shadow or thief. However at 26% crit without a mundus stone you will get more damage overall by going with shadow.
25% crit and shadow = 30% crit with Theif.
@Brasseurfb16_ESO the point you were trying to make is correct but the math you listed was a little unclear and didn't seem to support it(I think you just forgot to put in the noncrit component when you typed out your math).
If I perform 100 attacks(which noncrit for 100 damage each) with 50% crit and the 10% crit damage from The Shadow stone my total damage is: (100+100*1.1*0.5)*50+50*100=12750
If I perform 100 attacks(which noncrit for 100 damage each) with 55% crit my total damage is: (100+100*0.5)*55+100*45=12750
If I perform 100 attacks(which noncrit for 100 damage each) with 50% crit and the 10% crit damage from The Shadow stone plus the 10% crit damage from the Hemorrhage Nightblade passive my total damage is:
If I perform 100 attacks(which noncrit for 100 damage each) with 55% crit and the 10% crit damage from the Hemmorage Nightblade passive my total damage is:
Basically at 50% crit 'The Shadow' mundus stone and 'The Thief' mundus stone give equal benefit regardless of whether you are a nightblade or not.
If you have a crit chance below 50% you are better off with 'The Thief' mundus stone.
If you have a crit chance higher than 50% you are better off with 'The Shadow' mundus stone.
You might reconsider your calculation Armitas, because the critical damage bonus applies a 10% dmg modifier to the critical portion of the skill. So your 10% is realy in fact only a 5% increase.
DPS * (100% - Critical Chance) + (DPS* Critical Chance * Critical Bonus Damage)
I was speaking purely in terms of pve, as it is well known that stacking crit is inefficient in pvp. There are far better mundus stones for pvp purposes than either of the two.untill your pvping as every one (worth to be considered) is using crit resistance traits thief is allway inferior to shadow as you´ll only crit on guaranteed crits.
My crit rate sits at 74% right now and I feel like I'm wasting a mundus stone use that could be spent better. I'm a V12, bow using, medium armor nightblade. What stone would give me the best burst damage? Warrior? Right now its Thief I'm using.