Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

How does it work?

Should I use it?

If so, when?

I have it on all the time on my casters.

But then I don't have any casters with combat expertise. I'd just rather not have AoOs against my already lowish AC to grind away at my mirror images and premonition. I trust my concentration skill more.

I too began to have it turned on all the time on Sirion. Don't have any alternative and too high concentration skill to ever fail, so why not. Took me over a year to realize I should enable it.

How it works? In short it means people attacking youdon't get free attacks when you cast spells.

Just like when you move in combat and someone attack you, they'll get an Attack of Opportunity unless you beat a Tumble save, when you're casting a spell someone attacking you will get an Attack of Opportunity. But if you have Defensive Casting enabled you will get that save to avoid the Attack of Opportunity. For casting this save is Concentration which for reasons you can see on that page you'll want to max anyway if you plan to be casting in combat.

There's a table on the AoO page on NWN2 Wikia that shows your chance to succeed these saves with different character and spell levels.

Okay awesome, thanks guys

How about using with a Warlock?

always on on my lock

It works the same for the warlock and is perhaps even more important since you are casting spells non-stop.

It's a concentration check vs DC 15+ Spell Level. Once you have 23 concentration you cannot fail the roll.

Note that if you fail the roll the spell is entirely lost, but your opponent(s) still do not make an Attack of Opportunity against you.

The Combat Casting feat gives you a +4 circumstance bonus to concentration for spells cast in this manner.

Tsidkenu wrote: The Combat Casting feat gives you a +4 circumstance bonus to concentration for spells cast in this manner.

Useless feat, to be honest. As long as you max out concentration (you want to do this anyways, in case you are hit by damage), once you reach level 20 you have 23 skill even without any gear and only 10 constitution.

And a lot of caster gear comes with concentration anyways. And then there's bear's endurance and greater heroism.

So yeah. Unless you need it for a class requirement, ignore Combat Casting feat entirely.

At low levels it often makes sense to leave it off since Mage Armor + Shield = +8 AC... Once you hit level 5 you get IMA SpiderSkin for another bump in AC (not that you always want to spend the spell slots on defense, I certainly don't!) Once you get greater gauntlets of Concentration (+6 concentration costing about 10K in gold) and a few levels there is no reason not to have it on all the time. At level 7 with 10 CON your Concentration base will be 10 so if you have +6 gloves you have 16 Concentration, 18 if you cast Bears Endurance. This means up to level 4 spells can be cast with no chance of failure (you can only cast level 4 spells at that point). Obviously you may not be lucky enough to find or afford greater gloves of concentration by level 7, but even with the regular gloves of concentration (+3) and bulls you have a very low chance of failure and it's likely you can find some other items that give a slight bump here or there.

A final note that if you get hit during the normal attack sequence while casting a spell it can still disrupt spell casting so your desire for high concentration never goes away. Stopping at 23 to be immune to failure from defensive casting would be a mistake.

+1, always on. The chance of failure seems like 1/200.