A SkyProc Patcher
v0.1
What it does:
I built this tool to extend some of the common leveled lists (Bandits, etc.) with higher level NPCs. Many of the most common enemies you fight in the game cap off around 25, meaning the game becomes very easy at higher levels even without exploiting any of the less balanced features. The first version I built for my own use added +5, +10 and +15 level variants of Bandits, Falmer, Draugr, and Forsworn. In my experience most of the enemies you encounter are from these lists.
This test release adds user customization of the process and includes options for altering the spawn levels of the existing enemies. This is done using SkyProc to create a patch based on your load order, making it theoretically compatible with whatever mods you have installed.
Example Results:
If run using the default settings, the patcher will add 3 tiers of NPCs to each of the types listed above. Each one will be 5 levels higher than the last and (as in vanilla) will start spawning when the player reaches its level.
If you change the setting for NPC levels per tier to 10, the Bandit spawns would look like this:
-At level 25, Bandit Marauders (level 25) start spawning as in vanilla.
-At level 30, the first tier of new Bandits will spawn but be level 35.
-At level 35, the second tier of new Bandits will spawn and be level 45, etc.
If you define an offset of -5, existing enemies will start spawning 5 levels sooner. So the level 25 Bandit Marauder will begin spawning at level 20.
Downloads:
The first (best, in my opinion) option is to download the SkyProc patcher and run it on your load order with your own custom settings. It's available here on Dropbox for the moment:
http://dl.dropbox.com/u/45455626/ECLLv01.zip
Patch Instructions:
-Unzip the contents to your Skyrim\Data\ folder.
-If you already have a "SkyProc Patchers" folder it'll ask you to merge, say yes (nothing will be overwritten).
-Run ECLL.jar to start the patcher. It will generate a ECLL.esp file in your Skyrim\Data\ folder.
-Add ECLL.esp to your load order (at the end -- the patch was built based on your existing load order) using the tool of your choice (SkyrimLauncher, NMM, etc.).
Config File Info:
Spoiler
The file config.ini allows you to change a number of settings that control how the lists are altered. I'll go over them all here. Default values are listed with each setting.
[config] section
numTiers=3
The number of new "tiers" of NPCs to add. A "tier" is a leveled type of a certain enemy, like a "Bandit Outlaw" or "Forsworn Plunderer." If you just want to use one of the list offset features listed below, you can set this to 0 to not add any new NPCs.
LvlsPerTier=5
Each new tier is this many levels higher than the previous. For example, with the default of 5 the 3 new bandits will be levels 30, 35, and 40 (the highest level vanilla bandit is 25).
spawnLvlsPerTier=5
When added to the Leveled Lists, this number will be added to each tier's spawn level requirement. In other words, with the default of 5 the 3 new bandits will spawn when the player reaches levels 30, 35, and 40. I've included this as a separate variable because some players might want to increase the challenge by having, for example, the following table of spawns:
At level 30, spawn level 35 bandit
At level 35, spawn level 45 bandit
At level 40, spawn level 55 bandit
Which you could get by setting LvlsPerTier to 10 and spawnLvlsPerTier to 5.
allListsOffset=0
This allows you to offset the spawn level of every list entry in the game. For example, if you set this to -5 the highest bandit (level 25) would spawn when the player reaches level 20. It's basically a spawn difficulty offset. This runs after the addition of new tiers and will include them.
delevelAllLists=0
Basically the same as setting the above to -9999, setting this to any non-zero value will set the spawn level of every enemy in the lists to 1. This means that at level 1 the player has about an equal chance of encountering a lvl 1 Bandit as a level 25 bandit. Provided for players who don't like dynamically leveling environments and would prefer the realism of encountering skilled enemies from the start.
Remember, this will make it very hard to initially level up your character (also I haven't tested it with a level 1 character yet).
skipDragons=1
Ignore dragons when going through the leveled lists for the above 2 settings. With the popularity of various dragon-related mods out there, I felt altering their leveled lists was probably not a great idea. Set this to 0 if you want either the list offset or full deleveling to work on dragons.
[naming] section
By default, the patcher will grab the name of the highest tier of an enemy and add +1, +2, etc. to the end of it. You can manually enter names for each tier if you like.
useSuffix=1
Use the +1, +2 system by default. Set this to 0 to use the custom names.
bandit1=somename
bandit2=somename
...
draugr1=somename
...etc...
Use these to define the names for each tier of each type of enemy. By default I've included space for 3 tiers worth of names (the default), but if you increase numTiers you just have to add "Bandit4" and so on.
Example Configs:
Just some examples of things you might want to do with the settings.
Only delevel, no new tiers:
[config]
numTiers=0
LvlsPerTier=0
spawnLvlsPerTier=0
allListsOffset=0
delevelAllLists=1
skipDragons=1
"Hard Mode"; decreases the spawn levels of everything by 5, then adds 3 new tiers at levels much higher than the player levels they spawn at.
[config]
numTiers=3
LvlsPerTier=12
spawnLvlsPerTier=5
allListsOffset=-5
delevelAllLists=0
skipDragons=1
[config] section
numTiers=3
The number of new "tiers" of NPCs to add. A "tier" is a leveled type of a certain enemy, like a "Bandit Outlaw" or "Forsworn Plunderer." If you just want to use one of the list offset features listed below, you can set this to 0 to not add any new NPCs.
LvlsPerTier=5
Each new tier is this many levels higher than the previous. For example, with the default of 5 the 3 new bandits will be levels 30, 35, and 40 (the highest level vanilla bandit is 25).
spawnLvlsPerTier=5
When added to the Leveled Lists, this number will be added to each tier's spawn level requirement. In other words, with the default of 5 the 3 new bandits will spawn when the player reaches levels 30, 35, and 40. I've included this as a separate variable because some players might want to increase the challenge by having, for example, the following table of spawns:
At level 30, spawn level 35 bandit
At level 35, spawn level 45 bandit
At level 40, spawn level 55 bandit
Which you could get by setting LvlsPerTier to 10 and spawnLvlsPerTier to 5.
allListsOffset=0
This allows you to offset the spawn level of every list entry in the game. For example, if you set this to -5 the highest bandit (level 25) would spawn when the player reaches level 20. It's basically a spawn difficulty offset. This runs after the addition of new tiers and will include them.
delevelAllLists=0
Basically the same as setting the above to -9999, setting this to any non-zero value will set the spawn level of every enemy in the lists to 1. This means that at level 1 the player has about an equal chance of encountering a lvl 1 Bandit as a level 25 bandit. Provided for players who don't like dynamically leveling environments and would prefer the realism of encountering skilled enemies from the start.
Remember, this will make it very hard to initially level up your character (also I haven't tested it with a level 1 character yet).
skipDragons=1
Ignore dragons when going through the leveled lists for the above 2 settings. With the popularity of various dragon-related mods out there, I felt altering their leveled lists was probably not a great idea. Set this to 0 if you want either the list offset or full deleveling to work on dragons.
[naming] section
By default, the patcher will grab the name of the highest tier of an enemy and add +1, +2, etc. to the end of it. You can manually enter names for each tier if you like.
useSuffix=1
Use the +1, +2 system by default. Set this to 0 to use the custom names.
bandit1=somename
bandit2=somename
...
draugr1=somename
...etc...
Use these to define the names for each tier of each type of enemy. By default I've included space for 3 tiers worth of names (the default), but if you increase numTiers you just have to add "Bandit4" and so on.
Example Configs:
Just some examples of things you might want to do with the settings.
Only delevel, no new tiers:
[config]
numTiers=0
LvlsPerTier=0
spawnLvlsPerTier=0
allListsOffset=0
delevelAllLists=1
skipDragons=1
"Hard Mode"; decreases the spawn levels of everything by 5, then adds 3 new tiers at levels much higher than the player levels they spawn at.
[config]
numTiers=3
LvlsPerTier=12
spawnLvlsPerTier=5
allListsOffset=-5
delevelAllLists=0
skipDragons=1
ESP Only Version:
Alternatively, I've built a few different patches based on a clean load order (just Skyrim.esm and Update.esm). These should work fine with other mods unless they also alter Leveled Lists for any of the creatures listed at the start of this post. Use these if you aren't comfortable using a SkyProc patcher for whatever reason. Also hosted on Dropbox for now. Description of these prefab plugins:
-"Default" ECLL is made with the default settings. Adds 3 tiers of enemies at 5 level increments.
http://dl.dropbox.com/u/45455626/ECLLv01_plugin.zip
-"Hard" ECLL adds 3 tiers of enemies that spawn at 5 level increments but increase by 10 levels of strength each tier.
http://dl.dropbox.com/u/45455626/ECLLv01_plugin_hard.zip
-"Very Hard" ECLL adds 3 tiers at 5 level spawn increments that increase by 12 levels per tier and then decreases the spawn level requirement for all NPCs by 5.
http://dl.dropbox.com/u/45455626/ECLLv01_plugin_veryhard.zip
To install these, copy the contents of the zip into your Skyrim\Data folder and then activate the esp like any normal esp mod.
Other Stuff:
This version only covers 4 enemy types. I'm considering adding the "Mage" enemy type (Warlock in the editor), but I didn't do it for the first version because Mages already have 7 tiers going up into the 40's. Others I'm considering are Thalmor and Vampires, however I didn't bother because I haven't run into either of these as enemies more than once or twice in my time playing the game. If anyone has suggestions about enemies that should be included let me know.
If anyone would like to suggest some proper names for the new tiers of each of the enemy types I'd be happy to put them in the default config.ini. It uses +1, +2 etc by default but I included some (stupid) custom names in the .ini just as an example of how to set it up.
Why no Nexus? I put this together for my own use, really. After it was working I thought maybe others might find it useful if I stuck in support for a config file. If there's enough interest I'll get it up on the Nexus too.
Finally, please let me know if you run into issues. I've tested the patch output (with a level 100 character I managed to get every type of +3 enemy to spawn) and examined it in the CK, but I can't be 100% certain that I didn't miss some issues.

Does it create new NPC variations, then? The only consideration there is dealing with the face export issue (which should probably be built into skyproc).