Mold Earth, Cover and CR

[ZenBear]

By my estimation, it should be possible for a caster to use Mold Earth to make a small trench that can be used as cover. I've placed this ability on a homebrew monster that I'll post later, but what I'm concerned about is whether or not the ability to create cover at-will on a monster with ranged attacks ought to change its CR. My current thinking is that a trench created with Mold Earth would grant half cover to a Medium sized creature, and three-quarters cover to a Small creature, and since the monster is a Small creature it will be getting +5 to AC and Dex saves pretty much all the time. I built the creature to be CR 1/2, but if its effective AC is 5 higher then that sends it up to at least CR 1 if not 2. I can tune down its HP and rule that the trench grants half cover for Medium and Small creatures, but I like where the monster is at right now.

Thoughts? Do you allow Mold Earth to be used in this way? Do you think a trench would grant a cover bonus against melee attacks? As I understand it, RAW cover works for melee and ranged, but in my mind that really doesn't make much sense.

 

[Cap'n Kobold]

Creating a trench or foxhole is well within the capabilities of the spell. It would give cover to ranged attacks (and the inhabitant could probably claim total cover if they just crouched within it.)
However it would limit actions as well: difficult ground or perhaps half your movement to get out of it, crossbows, blowguns and spells are about the only thing that you can effectively use out of it, and in melee, any cover bonus is probably negated by your opponent having a higher position than you.

So it takes an action to use, and doesn't grant hugely great bonuses.
I wouldn't increase the creature's CR directly, however I would take the spell into consideration when deciding the situational modifiers to the encounter. - An encounter with them would be much more likely to consider them to have advantageous conditions if it plays to their strengths.

 

[DEFCON 1]

I personally wouldn't consider a trench to be three-quarters cover, only half.

To get three-quarters cover you need to be behind things like arrow-slits-- where almost your entire body can remain covered at all times while you fire out from behind it. Being in a trench is the same as being behind a short wall-- your entire upper body becomes uncovered when you poke your head and arms up to fire from behind it so only half your body is behind cover. That's only a +2 bonus to me, not the full +5.

So I personally wouldn't feel the need to increase the creature's CR, because for the most part having half-cover available almost all the time is what is always happening anyways. Most ranged combatants can almost always find half-cover (behind rocks, leaning out from behind trees, behind doorways etc.), so your Mold Earth creature is not gaining anything all that monumental that it wouldn't already be able to usually get. At least, based upon how my games tend to run.

 

[Paul Farquhar]

Have to agree with the others, a trench would be half cover, irrespective of the size of the creature. It's not the size of the cover that matters, it's how much the creature needs to expose itself in order to fight.

It also wouldn't normally count against melee, since the meleer would simply move down into the trench to attack. It would probably count as difficult terrain though.

So no, no change to CR.