Ovinomancer said:
Quite right! So, lets see, I'm building a new campaign world and to balance the usage of entangle I can only make about 30-50% of the surrounding terrain constist of mainly plant life. The rest should be inhospitable to humanoid life. Wow...not much room there for my rolling grasslands, my elven forests, my wooded hills, my swamps, my jungles, or any croplands to feed inhabitants. Or, maybe I should just limit where my players can adventure. Yeah, that's the ticket! I'll just make all most of my adventures dungeons or in the mountains, or along that rocky stretch to the east! Perfect! Take that pesky 1st level spell! [/sarcasm off]
Your sarcasm is misplaced. Let's take a look at the environments you list:
1. Rolling Grasslands. AFAIK, there are pretty much two types of grassland (not counting golf courses which should be about as entangle friendly as an asphalt parking lot): sparse and thin grass mixed with weeds that grows to maybe knee height and tall prairie grasses like I read about on the great plains. Where I live and on the west coast of the US, I've pretty much only seen the first kind.
Now, I find it difficult to believe that the first kind of grass is what the writers had in mind when they specified a normal DC 20 strength check, so if I were running a game, I'd seriously consider reducing the strength check in that environment. In the second kind of environment, I would give the DC 20 strength check but whenever you're dealing with 4-6 foot tall grasses, line of sight becomes an issue. Such an environment would be extremely suboptimal for entangle because you would be unlikely to see normal sized enemies until they were on top of you (unless you were mounted or something) and enemies who were entangled, could hide themselves pretty effectively by dropping prone. Since you're not likley to be going in there to melee with them, this makes entangle more of a delaying tactic against infantry in the prairie enviroment. (And mounted combatants should be able to get out of the area in one round if their mount makes the save or use ranged weapons without the entanglement penalties if their mount fails the save).
So rolling grasslands don't need removal to keep entangle balanced.
2. Elven forests
If these are like Lothlorien in the LotR film or like the pacific redwood forests, ground cover is actually quite sparse. If you're hiding in a patch of bushes and the entangle goes off, you're screwed but the areas that people are likely to walk upon are mostly moss with a few ferns. There's plenty of room to avoid an entangle spell.
3. Wooded hills
As distinguished from forests, I can only assume that you mean more open wooded areas with generous amounts of grass. In that case, the majority of the area will be similar to the grasslands: either it's easier to break out of or it blocks line of sight. The primary difference will be that trees will provide cover in addition to concealment.
4. Swamps
I don't have a lot of experience with swamps, but if the swamp contains generous amounts of water, it's likely that PCs or NPCs will be traversing it in boats. No plant-life in a boat. In a lot of other swamps, PCs or NPCs will be able to use the water for cover while entangled or will have concealment from tall vegetation. (Bullrushes and such would provide many of the same challenges as high grass from what I can tell: they'd entangle enemies really nicely but it's difficult to spot enemies before they're at the edge of the bullrushes and are easily able to get out if they save.
5. jungles
From everything I've read about thick jungles, they should present very severe line of sight issues for PCs using entangle. Sure, the environment would make entangling a very three dimensional effect (and therefore useful against flying or climbing foes), but your 40' radius is wasted if you can only see ten feet in front of the guy with the machete. In this environment, I would expect entangled foes to often be in *melee range.* The spell would hamper them if they stayed put and fought but, on a successful save, they would be able to get out of it (though it might cost them some AoOs).
6. Any cropland
In terms of entangle, I don't think this is really distinct from grassland except that it is likely to have more paths around it and to be more sharply defined. If your cropland is tall grains like midwestern cornfields, then line of sight issues should prevent the spell from getting too out of hand. (How exactly are you going to spot a spread-out group of five orcs moving through the cornfields until they're right next to the trail?) And, it will certainly have vegetation-free paths for the farmers and their horses as well as heavily traveled areas around the well, etc.
On the other hand, if your cropland is a lettuce field....I'm afraid entangle just isn't going to do much if anything. And my observations of pastureland--either for the cattle in the California hills and valleys or the sheep of the Lancashire countryside is that the animals tend to graze the grass down to at most soccer field height. You'll only get good use out of entangle on fallow pastures.
So, even assuming that all of the encounters are outdoors and in those kinds of terrains, you don't need to have entangle get out of hand. A strong focus on the requirement for vegetation in the area, a reduced DC for sparse or weak vegetation, and paying close attention to line of sight will help to control the spell. As an added benefit, paying close attention to line of sight and other terrain issues will also help your games to feel more varied and cinematic. If you put a large rock in the middle of the meadow for the orcs to flee the entangle, PCs can jump onto it to gain higher ground against their enemies. And the image of bugbears springing from the cornrows and then vanishing back into concealment is a lot more dramatic than "you're attacked by a pair of bugbears in a generic cropfield."
But when you consider that, in most campaigns, a lot of battles will be fought in towns, dungeons, city streets, rock quarries, towers, castles, and mines where entangle will be of no use at all it's not that bad. Furthermore, of the battles that do occur on entangle friendly terrain, some of them will be against foes like hippogriffs, vrocks, and air elementals who are not particularly vulnerable to it and some will even be against foes like that blaster wizard you mentioned who will say "thanks, I was worried about your fighters coming to get me but...not any more; it'll take them four rounds to get through then entangle spell. Eat fireball suckers."