Yesterhaven

This map is an official release, and therefore part of the canon lore of Aranna.
It was released in 2002, which means it was released for vanilla DS1, not DSLOA. In fact, there's a little incompatibility (both LoA and Yesterhaven edit the spell_turret.skrit; at fault is the Lich Lord's attack), which was fixed in the above NexusMods link already. However, in case you have an original Yesterhaven.dsres file and want to keep it, I've made a little standalone fix, which I'll upload & link to later.

On the Yesterhaven map, you start in the ruins of the town of Yesterhaven and are transported back in time to save the town three times in a row - from the Ice Queen, the Lich Lord, and the Fire King. Hence the story has three chapters. In the end, you get transported back to your own time - Yesterhaven lies in ruins again, but this time peaceful ones.
In each chapter, the town of Yesterhaven looks differently (snowy, swampy and dry), the NPCs change, etc. As the Dungeon Siege engine is not practically suited to change an entire region in-place, these changes are implemented in a necessarily clumsy but rather interesting way: There are simply 5 Yesterhavens - initial ruins, snowy, swampy, dry, and end ruins. At the end of each chapter you come "back" to the town via the "looping" path, not via backtracking.

The Yesterhaven map is multiplayer-only. There's no clear reason given for this. Maybe they wanted to avoid player confusion, or break of immersion, that would occur if you had multiple characters or mules and left some of them in Yesterhaven and then found out that the mules are still in "Snow Yesterhaven" while the rest of the party is now in "Swamp Yesterhaven". Another reason might be that there's a savegame issue with something on the map? Maybe the nodal texture swap of the initial obelisk or something? I don't know.
Actually the best way to prevent this issue would have been to make it singleplayer-only, and not provide any companions or mules. But maybe they wanted to support multiplayer because it's supposed to be an extension of the Kingdom of Ehb story, so you should be able to play with your KoE character. Then however I don't understand why they only provide Normal mode and not Veteran or Elite.
The problem of players being in the "wrong" Yesterhaven is, of course, still present in multiplayer, because players can (and need to be able to) start in either of the 3 levels. (The start positions are called chapter 1, chapter 2 and chapter 3.) And to remedy this issue, there's a rather hacky solution: When a player joins in a wrong chapter, additional town gates open up, and beyond them lies an elevator that leads to the next chapter - from Snow Yesterhaven up to Swamp Yesterhaven, and from there up to Dry Yesterhaven.

Putting the problems with the basics aside, the details of this map are wonderful. The snow environment, the undead valley and dungeons, and the fiery mountain, are all done with a lot of love, adding lots of new enemies like snow Krug and fire Krug, and a lot of effort was given to the three bosses, especially the Ice Queen and the Fire King, to make them interesting. As the storyline unfolds you learn step by step how the whole situation came to pass, what's up with Dante and the Undertaker and so on, the storytelling is really good.

Conclusion: singleplayer would have been the better choice, but please ignore it and play along with the map design, and enjoy an amazing adventure in the world of Yesterhaven! Can't believe it took me 20 years to try out this little gem!

Picture time!

Snowy Krug on the way up Mount Wintershroud:

The phantastic Crystal Towers:

The Snow Queen:

The haunted forest in the Valley of the Dead:

The Lich Lord:

Yesterhaven in dry-grass look:

The sunbaked way to the fiery Mount Underforge:

The even hotter bowels of said Mount:

Nice region design where you walk past the entire Citadel of Ash, spotting the Chalice of Mourning on the way, before you enter it:

The Fire King:

Pretty cool ah? A lot of modeling work, with all the unique terrain they added for the Crystal Towers and the Citadel of Ash.
The only type of artwork that this map is missing, but which is featured in Return to Arhok, is voice acting.

I also made an overview map for Yesterhaven, now included in this download: https://www.nexusmods.com/dungeonsiege1/mods/163
(I allowed myself a slight inaccuracy, I portrayed the Yesterhaven ruins at the beginning & end as the same region, they are actually two separate regions, but I found the map just looked nicer like this.)

Here's my LoA fix - I've uploaded it to my Minimods collection: https://www.nexusmods.com/dungeonsiege1/mods/114?tab=files (download Yesterhaven-loa-fix.zip)

Eksevis was so kind to add my German translation to the NexusMods page of Yesterhaven https://www.nexusmods.com/dungeonsiege1/mods/64?tab=files

I like playing the single player DS2 version in Iryan's legendary Mod