I'm not sure if this is a bug, or just something I don't understand. I'm only a couple hours into a playthrough and wanted a Nighteye spell. I purchased one from a vendor in Sadrith Mora mage's guild that I currently do not have the skill and magicka to cast. In Morrowind, you could then go to a Spellmaker and create a custom spell that you COULD cast that was of a lower value or lesser amount, etc. When I go to a spellmaker after doing all this in Morroblivion, the Nighteye spell does not even show up in the list. I was hoping to make a less powerful version I could cast, but the spell effect isn't there at all.
Am I doing something wrong, or is this a bug?
It's a "feature" of the TES4
It's a "feature" of the TES4 game engine -- high level spells are considered "skill perks" which are unlocked at Apprentice (25 skill), Journeyman (50 skill), Expert levels (75 skill). You can not enchant or make custom spells based on those spells until you've unlocked the corresponding perk. A low level alternative to the Nighteye spell is Light (self).
In discussing game design theory -- you might say this is an okay tradeoff in order to balance the fact that there is no longer a spell failure mechanic in TES4 (not to mention the constantly regenerating Magicka). And indeed, even with those Locked Spells / Skill Perk, TES4 allows you to spam Cast like no ones business compared to Morrowind. I've thought about unlocking all morrowind spells to be available at game start but then the game would become even more unbalanced.
It really annoyed me at first too, until I realized that I was just feeding into my autistic need for consistency and intolerance of surprises, heh.