After almost 20 years past its release date, Elder Scrolls fans still sing praises for the series' third entry, Morrowind. This is for good reason. Morrowind had a lot of unique characteristics not shared by any other Elder Scrolls game, especially when it comes to the game's magic system. There are plenty of Morrowind spells that could be recycled in The Elder Scrolls 6 to make it a better game - many of which weren't featured in Skyrim.
Morrowind has one of the most unique magic systems out of any Elder Scrolls game. The classic western RPG was stuffed with unique spells and spell effects for players to experiment with. It also enhanced its regular magic system by way of the game's custom spell creator, which allowed players to stack up to three different spell effects onto a single cast. With the right stats, this could result in some extremely silly or downright broken spells. Many of them would not be so broken if not for the spells which didn't survive the move towards Oblivion and beyond.
The Elder Scrolls Wiki has a full list of Morrowind's spells, but the most fun inclusion for The Elder Scrolls 6 would definitely be Levitate. It is the ability to move freely in the air for a duration of time, and is ostensibly flight - and it's right at the player's fingertips in Morrowind. Forget riding on Skyrim's dragons, which players don't even get to control, Morrowind lets them leap a mountain if they really want to. Imagine how easy reaching Skyrim's Grey Beards would have been if The Elder Scrolls' Dragonborn could simply float up the mountainside. There's no need to mention how useful it would be for navigating dungeons and evading melee attacks, especially if TES6 implements an area like Blackreach.
TES6 Needs Morrowind's Spell Creator
Another spell from Morrowind that would be useful in many situations in The Elder Scrolls 6 is Spell Reflect. Much like Levitate, Spell Reflect's name is self-explanatory - it reflects spells. This is a useful tactic for anyone trying to pull a fast one on spellcasters. There's no need to worry about evasion when anything they send at the player is coming right back towards them. It's like an arcane version of tennis where the player never misses a swing and their opponent dies a painful death. Bethesda removed a really fun idea for a spell effect by getting rid of Spell Reflect, and TES6 would benefit from its inclusion.
Finally, the most useful out of any of Morrowind's spells is actually a two-spell combo. The married pair of Mark and Recall are incredibly handy hexes to keep on hand. Using Mark, the player can pinpoint any position they desire. Then, all they have to do is use recall and they will instantly be transported back to that spot. This may not be super useful for long-range travel in TES6, since it will likely have Bethesda's modern fast travel, but it would make navigating large dungeons and towns incredibly efficient, since the player could mark and transport to different locations at will.
There are still many more unique spells that Morrowind has to offer, and even more when one considers all the custom spells that they can create. More so than the individual spells themselves, Morrowind's spell creation system is its most interesting tool. Even without spells like Levitate (which is broken on its own), The Elder Scrolls 6 would benefit from the player's ability to stack mundane spell effects on top of each other for an awesome combination. It allows for more creativity in the way mages can be played, and makes the game more interesting overall.