I found some equations over on stratics for chance to hit. Here they are. I'll go into how important these are shortly.

FORMULA:

Hit Chance% = ( ( [Attacker's Combat Ability + 20] * [100% + Attacker's Hit Chance Increase] )

divided by

( [Defender's Combat Ability + 20] * [100% + Defender's Defense Chance Increase] * 2 ) ) * 100

That looks annoying to mess with.

**This is probably the most important formula for PvM meleers and every single type of pvper.**

So before AOS the system on chance to hit was a simple comparison of your fighting skill vs their fighting skill. If you were both at GM, it was a 50% chance to hit. The way the formula here works though is really different. HCI and DCI are incredibly powerful. The relationship between skill and HCI/DCI is multiplicative though, so you really need both (skill and HCI or DCI)...

So every single pvp or archer out there runs more than 30 hit chance increase. It's likely that they run 45. Let's assume they run 45... if they don't run about that much, then they're trash and you should be able to easily kill them regardless of your DCI.

Let's assume that you and they both have 45 HCI.

You're getting hit

They have 45 HCI, you have 0 DCI,

72.5% chance to hit.

How many of you necro mages out there run 0 DCI? How many of you have 120 magery for your mage weapons? If you have 110 skill and 0 DCI it's 78% chance to be hit. That really sucks. You're going to get owned.

If you have 45 DCI and they have 45 HCI,

you have a 50% chance to be hit... that's a huge improvement. 45 DCI might cost you a bunch of mana regen or require that you change your template. If you're ever taking damage in pvp, you'll be screwed without DCI.

Let's say you have 0 DCI, they have 45 HCI.. and Hit lower D. on their weapon. This stat has a chance to proc (to take effect) on you based on whatever percent they have... my kryss has a 48% HLD... so 48% of my swings will lower your DCI. It lowers it by 25... So let's say HLD has taken effect on you with 0 DCI...

**That's a 97% chance to hit.**That's insane. You're going to get owned... like... hard... in the face. You can't ever let yourself get hit that often... as a dexer anyway... as an archer it might be ok to run no DCI... As a mage? I couldn't play with no DCI.

Let's say you have 30 DCI when you get hit with HLD, it drops your DCI down to 5%... and you will be hit 69% of the time. That is sooo much better than being hit 97% of the time.

Every geared pvp dexer (every dexer worth anything runs HLD) will have 40+ HCI and HLD. If you don't gear DCI, you're screwed. You'll always get owned. Dexers deal more damage per second than mages and archers and if you can't avoid that damage you're going to die.

**How this affects PvM**

I think most monsters have under 100 fighting skill. According to Stratics, dreadhorn for instance, has 93 wrestling. So let's assume mobs have 100 fighting skill for our calculation... and a Five on Friday recently said they don't have hit chance or defense chance. If you have no DCI, they have a max chance to hit you around 40%. If you have max DCI that chance to be hit drops to 30%. If you have 120 Parry and no bushido, with a shield, your chance to avoid taking damage on each swing would be less than 20%. If you had 120 parry, 120 bushido, and a 2handed weapon, then your chance to be hit would be just over 16%.

Imagine a character in a 70's suit with max DCI, 120 fighting skill, 120 parry, and 120 bushido. They'd have less than 16% chance to be hit by melee damage from most monsters. Now imagine if they had life leech on their weapon or were running vampire form. With HCI, 120 fighting skill, and were fighting against dreadhorn, you should have about a 90% chance to hit. 90% chance to hit, leeching a bunch of life on each hit, only taking damage 16% of the melee swings and taking lots of damage from spells (hehe). That's how those asian guys tank the dark father.

I'm not saying everyone in PAS that pvps should run out and gear DCI. I don't gear DCI on my necro dexer. I just bloodoath and take the hits. I'm not saying archers should gear DCI either. If you have a lot of trouble with dexers, consider getting it. It helps a LOT.

**Updated Comments for DCI on a Mage in PvP - 1/12/09**

I tried running 65-70 DCI recently on my mage. Gearing for it isn't as hard as I thought it would be. The idea behind this: After getting hit with HLD, you lose 25 DCI. That reduces 70 DCI to the cap of 45. If your opponent matches your fighting skill and has 45 HCI, then they have exactly 50% chance to hit. That's much better than the 70ish percent chance mentioned in the earlier parts of the post.

20 Aegis of Grace

15 Armor of Fortune

5 Quiver of Infinity

15 Ring

10 Spell book from invasion

65 DCI

If I were willing to use a shield, it'd be even easier. I recommend (with this setup) a shield with DCI and resists, like just one you'd loot and enhance. I like the SC wooden shields with bloodwood enhancement for 2 HP regen too.

It's powerful. I'm able to survive against dexers much better than before. The trade-offs are tough. I think I have about 2 mana regen, but with a few better items it wouldn't be so bad. I hadn't tried it before because I thought it'd be impossible to gear it to 65-70 without uber gear.