Another School of Magic for spells-without-level Lamentations.
This lists the Magic-User spells recorded within the final First Age tome written by Mordenkainen.
I Make Miscasting FUN!
Here are some semi-generic miscast tables by type of magic for use with spells-without-level Lamentations. They’re adapted from a list posted to the Lamentations forum by Andomedanaea.
These are immediately usable with Illusio Primo, White Dwarf’s Treasure Chest and Unearthed Arcana (as those Schools are drawn from First Age material). With a little thought they could be used with any spell from any School.
When a wizard miscasts, look at what type of magic the spell involves and roll on the appropriate table:
You could also press Dungeon Crawl Classics into service here. The tables for Mercurial Magic, Corruption and Spell Misfires (DCC/111-120, in my 4th print) are pretty great.