(Wind : Black Magic) Confuse: Target temporarily loses access to some spells and TP maneuvers.
INT check determines how many of each are blocked. Lasts up to 3 minutes.
(Water : White Magic) Inhibit: Reduces the power of a target's TP maneuvers and increases their ready time. TP gain is also lessened.
10-25% reductions for power and time based on a MND check. -Store TP and Subtle Blow+ for players would also vary. Lasts up to 3 minutes.
(Fire : Black Magic) Muddle: Reduces the target's Magic Attack and INT.
Variable between 10-30 MATK and 15-30 INT based on INT check. Lasts up to 3 minutes.
(Thunder : White Magic) Shatter: Reduces the target's Magic Defense and MND.
Variable between 10-30 MDEF and 15-30 MND based on MND check. Lasts up to 3 minutes.
(Dark : Black Magic) Spellbind: Reduces target's Magic Evasion and Magic Accuracy.
Variable between 15-30 based on INT checks. Lasts up to 3 minutes.
(Light : Black Magic) Regress: Reduces the target's level.
How many levels will depend on the INT difference, but this would mainly reduce all stats by the amount the players might gain through their own leveling and possibly weakening the strength of job traits if, say, the level down would take a mob from Evasion Bonus IV to III. EXP gain or skill up checks would stay at the mob's default level. Does not wear if landed, but can not be overwritten, either.
(Wind : White Magic) Panic: Target is compelled to run around in a panicked state while losing stamina.
Target will run around randomly in a 15 yalm radius at varying speeds from the point they're inflicted with the spell, losing 1% HP for every tick they're running. They will not attack or cast in this state, but taking damage from anything other than the spell's effect will bring them back to their senses. Can last up to 60 seconds.
(Earth : Black Magic) Bog: Target is knocked back with slight earth damage and their movement speed and evasion is encumbered.
Distance knocked back can be 5-20 yalms. Movement speed reduction can be 10-30% and Evasion -10-20. Damage should be somewhere between Stone II and III. Additional effects can last up to 45 seconds.
(Light : White Magic) Emanate: MP costs of spells cast by the target is distributed to party members and further deducted from the target's MP pool.
For example, if a mob casts a 300 MP spell, a percentage of 10-50% of that cost would be given variably to each party member in range (~15 yalms) resulting in a 180-900 MP loss for a party of 6 on top of the 300 spent to cast the spell. Lasts 2 minutes or 10% of the mob's Max MP.
(Dark : Black Magic) Pain: Physical damage done is reflected upon the target while reducing its ATK by that amount.
INT-based spell that reflects 10-25% of damage a mob does in attack back to it. If a hit does 300 damage, its next swing will be performed with -300 ATK, changing to -150 for the next round if that's how much it did as a result of that, and so on for the duration of the effect, up to 3 minutes.
(Non-Elemental : Black Magic) Ensanguine: Inflicts a powerful DoT that slows a mob's attack speed the lower its HP gets.
Thinking roughly 20-30 a tick with the slow effect being 1/3 the percentage of HP lost. So, a mob with 30% HP left would have a 23% slow. This would stack with other slow sources like Slow II and Elegy. Spell would last up to 120 seconds.
I'll stop for now. Things like Plague are also a bit of a given.