There is spell critical and weapon critical, you can see the % chance value you currently have in your character sheet.
If it says 12%, then, on average, 12 times out of 100 you will do critical damage. You can do more or less depending on your luck though.
Yes, critical damage is a bonus damage. Someone with the maths figured out can come along and post the exact formula, but it is roughly half the damage you actually do.
So let's say, you have an ability that does 3K damage, when it crits you'll get about 4.5K damage.
So yes, it is totally worth it to increase your critical chances.
You can do it in several ways:
1) use at least 5 pieces of Light Armor if you are a magicka build, use up to 7 Medium Armor pieces as each one will increase your critical rating if you are a stamina user.
2) Thief Mundus stone (both spell and weapon)
3) Armor sets: for Light armor you can craft Juliannos, Hundings rage and others for Medium Armor. Keep an eye on any set that might increase critical chances, there are many more.
4) CP points: 30 points in either the Apprentice or Atronach will give you either spell or weapon critical rating
5) Weapon traits: Precise increase all your critical rating (both spell and weapon)
6) If you are Dual Wielding: Daggers increase your weapon critical rating
7) For magicka users, Mage Light (2º skill on Mages guild tree), increase your spell critical by 10%. For stamina users Expert Hunter from the Fighters guild tree.
8) Be a Khajiit if you are a stamina build for 8% more weapon critical rating

A lot of people agree on the following: once you reach 50% critical chances (without The Thief), you might want to try the Shadow mundus stone (increase critical damage done)

Hope that helps

Arciris wrote: »

A lot of people agree on the following: once you reach 50% critical chances (without The Thief), you might want to try the Shadow mundus stone (increase critical damage done)

Hope that helps

I would counter that increasing base damage might be more useful as you always get Base Damage. But, the increase in Crit Damage is a percentage on top of a percentage. So, in other words, you get say 10% more Crit Damage, and you have a base of 1000, you do 1600 damage. But, if you increase your base damage by 10% to 1100 then you get 1650 from your Criticals, along with the extra base damage when you don't.

In any event, it is easy to swap out Mundus stones and see what works better for you.

I should know this by now but can someone definitely confirm whether the Thief gives a critical chance percentage or a critical chance rating figure, ie does it have the same impact on critical chance at lvl 20 as it does at VR16???

Waffennacht wrote: »

I was wondering, at exactly 50% is the shadow or the apprentice a better mundus choice?

Not enough information to advise. To answer that question you would need to look at your spell damage first. Consider the apprentice, with no divines it gives 166 spell damage. So if your spell damage is at say 3000 then you'll lose 5% spell power to gain 12% spell critical damage 50% of the time, which would probably lead to higher DPS. If your spell damage is closer to say 1600 then you'll be giving up 10% spell power to gain 12% spell critical damage which would probably lead to lower DPS

SirDopey wrote: »

Waffennacht wrote: »

I was wondering, at exactly 50% is the shadow or the apprentice a better mundus choice?

Not enough information to advise. To answer that question you would need to look at your spell damage first. Consider the apprentice, with no divines it gives 166 spell damage. So if your spell damage is at say 3000 then you'll lose 5% spell power to gain 12% spell critical damage 50% of the time, which would probably lead to higher DPS. If your spell damage is closer to say 1600 then you'll be giving up 10% spell power to gain 12% spell critical damage which would probably lead to lower DPS

Nice, thanks, conveniently the spell dmg number is 3000

RapturousRex wrote: »

What does critical rating mean? Is that jusy yhe % chance of hitting with a critical?

My understanding is that critical rating is a numeric value. You'll notice on some pieces that they state increase critical rating by xxx and other things specifically say %. When its critical rating, that fixed value will affect your overall % differently based on your lvl, this is because you require a high critical rating value at VR16 to achieve 100% than you do at say VR1. Does this make sense or have I just really confused you??

Ooh, so with that in mind, I've got 30CP to put on my level 8 Khajiit NB, I've put yhem in mighty and ignore phys resistance, so far, should I move them onto increase crit?