Environmental Dangers Analysis

A first level dwarven paladin finds himself stranded in a barren, sandy desert. He has magical access to food and water, but the heat bears down on him. Civilization is three weeks away. Fortunately he is made of tough stuff, and arrives back to civilization worn but still alive.

At fifth level fate conspires to dump the paladin in identical circumstances. He made it once before, and now he's tougher. Yet this time, he doesn't even make it two weeks before expiring on the sands. Why?

Fourth edition Dungeons & Dragons includes rules for "environmental dangers." It simulates the drain on a person in frigid cold, burning heat, or perhaps something supernatural like necromantic energy.

Every eight hours, a character exposed to such an environment must make an Endurance check. The target number is based on the environment, but varies from 21 to 30 based on the examples in the book. Each time a character misses the check, he loses a healing surge. If the character has no surges, they lose hit points equal to their level. Surges lost in this way cannot be regained until the character escapes the environment. Regaining hit points isn't mentioned, but I'm assuming you can't. (Given that most hit point recovery requires a healing surge, it's largely moot.)

I'm going to ignore that during the eight hour block in which a character takes an extended rest, the character receives +2 on their Endurance check; it will slightly extend my results below, but the core results will stand.

These general principles also apply to the rules for suffocation, thirst, and starvation. I haven't run the numbers, but the general results will stand.

The goals are obvious. Tougher characters, those with high Constitutions or who trained in Endurance, will survive better. Higher level characters survive longer as well, because they're just cooler. Hit point damage scales by level to keep high level characters from having obscenely long survival times.

It's the hit point scaling that causes our dwarf's problem. At low levels, the hit point damage goes up much faster than Endurance and total hit points increase.

Following is my analysis for several representative characters. First, let's introduce the characters. The "Base HP," "Base Surges," and "HP/level" are just out of the book. These examples have no feats, powers, rituals, or magical items.

Note that for all following results, the number has been rounded to the next tenth. Calculations were done using 32-bit values.

The easiest to calculate number is how many tests the character can make before dying. This is really just the number of surges plus total hit points divided by level.

This does show the problem, but it's not quite accurate because it ignores the checks. In particular gaining levels will improve the Endurance check, improving the character's staying power. However, it is amusing to note that our Dwarven Paladin can miss 50 checks at 1st level, but only 25.3 at 7th level.

To figure out an average actual survival time, I have assumed that a character takes damage from the pool of surges and hit points every check, but only a fraction based on their likelyhood of passing the check. So up against a target number of 26, a character with an Endurance of 10 will fail the check 75% of the time, each each check I simply apply 75% of a failed test. In reality the numbers will vary, but these will provide the average result. For the following I've gone with a target number of 26, suitable for frigid cold or stifling heat. The first table is the number of checks, which represent 8-hour blocks. The second table simply divides the results by 3, making the results in days.

Expected lifespan versus DC 26 (in 8-hour blocks)

Expected lifespan versus DC 26 (in days)

(A character can survive infinitely long (∞) when he always makes the environment check.)

So there is the biggest problem. Especially in the heroic tier, going up a level can actually make you worse at surviving a dangerous environment!

On the up side, it's relatively easy to limit the weirdness. First, ensure that the character always has at least a small chance of passing the Endurance check. Second, avoid the very low levels, maybe levels 1 to 3. Jumping from a 1/1 to 1/2 or 1/3 is a far steeper drop than 1/3 to 1/4 or 1/5.

The next problem is that you usually lose a bit of survival time on odd levels. This makes sense, as at odd levels you don't get a boost to your Endurance, which is the only thing improving your survival time. It's relatively minor, and it doesn't bother me.

The final problem is that the system as written tends to smack low Con or un-Endurance-trained characters extremely hard. As a simulation of a world, this works. It also makes sense from some story standpoints, where the tough warrior survives the harsh clime better than the average wizard. However, 4e is designed to balance in combat. Presumably the entire point of the dangerous environments system is to leave PCs a bit drained and weary before facing some dangerous challenge. Applied as is, this will leave the poor wizards in bad shape compared to their dwarven warrior friends. If you tweak the system to hit all of the PCs more evenly, you penalize the characters that chose to take higher Constitutions or to train in Endurance. I'm not sure what the happy medium here is.