Tall Creatures, Reach, and Cover

[IndySteve]

The following scenario came up in our game the other night:

A large, tall creature (Ogre) which has a reach of 10 feet had a PC 5 feet in front of him and another PC 10 feet in front of him. He attacked the PC 10 feet away and the player asked if he had cover from the other PC between the ogre and himself. I ruled that since the ogre was a tall creature and, as I saw it, mostly swinging down, there wouldn't be any cover. The normal rules for reach weapons state that the cover provides +4 AC bonus. I gave him a +2 AC bonus to compromise. Should the cover AC bonus for the PC have been +4, +2, or +0 and why? Thanks!

-Steve

 

[hong]

+2 sounds about right. It isn't +0, because the character in the middle will still block some of the ogre's view of the target. This is one of those situations that isn't covered explicitly in the book.

 

[Magus_Jerel]

The GM has to ad hoc the situation.

Some of the examples concerning cover work here -

there would be a +2 modifier.

It isn't +4 - as the ogre does have height...

but it isn's +0 - as the other PC is in the way somewhat.

 

[chilibean]

+2 seems to be a good call, but it could be argued whether it should be a cover or concealment bonus.

Since the "cover" in this case is actively moving and trying to avoid getting hit, he seems slightly less like regular cover and more like just something that is in the way of his vision. Something like 25-50% concealment maybe.

I'm not sure when it would matter whether you called it cover or concealment, but 3e has lots of stacking issues so it might become important in weird situations.

I'm sure someone here can tell you what the ramifications are between calling it cover or concealment.

 

[hong]

I'm not sure when it would matter whether you called it cover or concealment, but 3e has lots of stacking issues so it might become important in weird situations.

I'm sure someone here can tell you what the ramifications are between calling it cover or concealment.

By the rules, there's no such thing as a "concealment bonus" in 3E. Concealment is for situations like hiding and invisibility, where there's no actual physical barrier that stops you from hitting the target -- just that you can't see it well. This is handled via a percentage miss chance, as opposed to a bonus to AC.

 

[chilibean]

A 10% miiss chance is effectively identical to a -2 to hit. The only difference is that one requires 2 rolls and the other is built in to the attack roll. So if you gave them a bonus of +2 to AC, but only checked to see if you hit the "cover" on a miss of 2 (not 1 or 2), then it would be similiar to +1 AC from cover and +1 AC from concealment. Even though the concealment part should technically be dealt with as a 5% miss chance on a seperate roll by the rules.

But all this is just in case the ogre is throwing a grenade like weapon when it might matter where the miss went, and other situations like that.

 

[hong]

A 10% miiss chance is effectively identical to a -2 to hit.

No. You make the very common error of assuming a 10 percentage point change to be the same as a 10 percent change.

For example, suppose I have +5 to my attack, and my target has AC 20. I hit on a roll of 15 or higher, which is a chance to hit of 6/20 = 30%. Now if I have a 10% miss chance on top of that, 10% of rolls that would have hit will miss instead, so my overall chance to hit is 0.9 x 30 = 27%. However, if the target has a +2 bonus to AC instead of a miss chance, its AC becomes 22, and I need to roll 17 or higher to hit. My chance to hit is now 4/20 = 20%.

In general, a flat AC bonus (or attack penalty) penalises you less, the higher your chance to hit is. Suppose my attack bonus was +18 in the above example, so I need to roll only a 2 or more on d20 to hit AC 20. My chance to hit is 95%. If the AC becomes 22, it means I now need a 4 or more on d20, so my chance to hit becomes 17/20 or 85%. That's about a 10.5% reduction from what it was. By contrast, if I had a +2 bonus to attacks, my chance to hit would be 15% and 5% against AC 20 and 22 respectively. My chance to hit has been reduced 66.7% due to that +2 AC bonus.

By contrast, a miss chance is constant in its effects. No matter what your original chance to hit is, it's reduced by whatever proportion the miss chance happens to be.

 

[Faragdar]

Keep in mind that the ogre has natural reach, so you have to consider the rules for striking cover. He might accidentally hit and do damage to the intervening character. +2 AC from cover = good call.

 

[Archer]

Since the ogre would have +2 cover against the character 10' away the character has the same cover bonus against the ogre. Cover bonuses for melee combat are always the same for both combatants.