Description:

Sharn gra-Muzgob in the Balmora Mages Guild may have something to hide. 
Finishing her quest related to her technically legal activities will now grant you a reward actually worth being kept secret.

This mod adds:

1 New item: Soul Prism - it has 8 slots for souls. Equip it to manage these souls and to learn the new spells.
1 New spell effect: Transfer soul. Cast this on a filled soulgem to transfer that soul to your Prism. One way only.
8 New spell effects: 1 spell effect for each soul slot. Summons the respective soul for x seconds. They behave exactly like vanilla summons in almost every way, and their cost scales based on their health & magicka and your Willpower & Conjuration skill. These new spell effects also have custom tooltips!

All new spell effects are available for spell making & enchantments! The spell effects stack exactly how vanilla spells would.

Requirements:

Morrowind Script Extender - 2.1+ Nightly
MGE XE
Magicka Expanded - Framework only

How to Install:

Simply unpack it into your Morrowind installation folder and activate the SummonSouls.esp from the Launcher or any mod manager.

If you have already finished Sharn gra-Muzgob's quest related to her technically legal activities, you will have use the console to get the item. Open up the console and type:

player->additem "OV_SoulPrism" 1

How to Uninstall:

Delete OverlordMasterofAll folder from DataFiles -> MWSE -> mods & delete/uncheck the soulsummon.esp.
Additionally you can delete my icons located in DataFiles -> Icons -> GOMA if you really want to.

Changelog

0.51)
Changed the name of every global to make it basicly impossible that other .lua mods interfere.
Made the Transfer soul hitting a bit less strict. 
The big icon for Summon Soul 4 is less pathetic now.

Anyone updating from 0.5 to 5.1 -> the name change changes the adress of the soul index so... they are gone. Sorry.

Incompatibilities:

OpenMW and anything else not compatible with MWSE.
If you have a mod that changes or replaces Sharn gra-Muzgob's quest related to her technically legal activities you might have to use the console to get the item.
Obedient Summons: Patrol & wait will turn soul summons aggressive
Anything else should work.

Details:

Any spell which summons a soul will get an additional cost based on the health & the magicka (to a lesser degree) of that creature, which is displayed in the tooltip. 
Because spellchance can't be changed in the same manner (or at least i couldn't) i decided to reduce the added cost based on the players willpower & conjuration skill.
Entchantments do not gain any bonus cost based on the creature and are pretty busted as a result - have fun.

In theory any creature, be it from the base game, expansions or mods can be summoned, as long they can be soul trapped.
Which gets me to:

Known Issues:

Scripted Creatures keep their scripts which on one hand means that your fancy modded creatures will use their fancy special attacks (most of the time) - on the other hand it means that dagoth gares will invite you to the red mountain each time he's summoned and  will bless you with corprus when he dies.
What a nice guy.
Some scripts attached to the creatures might break or behave unexpectedly. The vast majority of enemies, including quest related ones are completely save though and the few exceptions are pretty obvious.
If i find a way to cleanse them from scripts i might.

Your summoned souls can be soul trapped. If i find a way to change it, i will.

Please let me know of any bugs, typos, wierd grammar, balance issues or ideas for improvements.

Future Plans

I'm planning on adding an actual quest to get the item. I'm sorry Sharn gra-Muzgob this kind of magic is just a bit out of your league. 
The different spell effects will be unlocked through those quest(s), until then all of them can be learned from the soul prism.
I also want to add a unique mesh & icon to the Prism and maybe make the menus not look so... functional.
I  also want to keep balancing it depending on the feedback.

FAQs:

How much is the additional cost actually?
The pictures were made when the cost was higher than it is now.
The cost formula at the moment is as follows (but still subject to change):
Additional Cost: (((health / 2 + (magicka / 15)) / 10) / (1 + ((Willpower + ConjurationSkill) / 100))) * (1 + summonDuration / 10)

But if that's too much/too little please post a comment and tell me!

I have finished Sharn gra-Muzgob's quest related to her technically legal activities and nothing happened. Are you a liar?

You should receive a "strange gem" in addition to whatever technically legal spell you choose as a reward. 
If that didn't happen, try to use the console to add it: player->addItem "OV_SoulPrism" 1
If the item has a regular tooltip, something isn't right with the required mods -> get the latest nightly version of MWSE, make sure the Magicka expanded framework is installed and MGE XE as well.
If the item didn't appear at all, check if you have loaded the .esp
If it's still not working, let me know.

There are already Summon Soul mods - one with almost the same name! Are you a thief?

There are 2 mods that provide vaguely similar functions:
1) Soul Summon v1: A mod from 2008 that hasn't been updated since and only works with base vanilla creatures, without any fancy MWSE stuff.
2) Obedient Summons : A great mod that lets you give commands to your summons as well as access to a spell that summons the creature directly from placed soulgems. The summoning is handled in a very different way though.
If you want vanilla style summon trapped soul spells (with some compromises) - get my mod!
If you want deeper summoning gameplay as well as a way to permanently bring a trapped soul back - get Obedient Summons!
If you want both - get both!

Are there creatures that can't be summoned?

There are very few creature that must not be summoned (like Dagoth Gares).
There are some creatures that start to talk to you when summoned (some quest related enemies) but they seem to stay under your control even if the original went aggressive after exiting the conversation. More testing is requiered to be sure - please provide feedback or any interesting finding if you want to!
In theory any creature with a soul can be summoned, but some heavily scripted creatures might break or behave unexpectedly.

Which abilities of the creature will remain from the original?

In case of modded creatures it depends on how their abilities are implemented, but generally speaking: Everything. If the creature was a merchant - their soul summon versions will be merchants too!
If they were able to speak about our Lord and Saviour Dagoth Ur you now can hear these sweet words when ever you want!
If they gave you a Daedric Crescent & teleported you to Divayth Fyr when they die, you've successfully found an exploit! 


Credits:

Spammer - for providing this great mod
OperatorJack - for the amazing framework that makes this even possible
MWSE & MXE Team 
Morrowind Modding Discord 
ChatGPT - the source and solution of most of the problems in this script.