I'll keep it short... is this subclass a complete waste in game? Finding that most of the illusionist spells, well.... either aren't in game or don't do much? Is there really a benefit to subclassing as an Illusionist? What is their kick/advantage? Please educate me.
All wizard subspecs outside evocation and necromancy are pretty trash, and necromancy is not far behind after they gutted Dance Macabre.
The problem with Enchantment/Illusion spells as well is that they face really crappy dice checks, if they fail they still eat up a spell slot, and most of them are mutually exclusive because all of them are slapped with concentration. Try landing Phantasmal Killer on any mob of note like a boss, which seems the exact target the spell is designed for as a recast spell, but it barely ever lands.
Most spells are garbage, that's why it's basically Chain Lightning, Fireball, Magic Misslies/Art of War, Hypnotic Pattern and Ottor's Irresistible Dance. Ice Storm is not bad either as an opener since it can cause aoe prone and rearrange the enemy turns. Spell balance is really poor. Circle of Death has less range and less damage than Fireball at the same spell level, much like most necromancy spells which seem to have lower damage and lower range under the assumption the summons make up for it, but they don't because summons don't scale, neither in HP or with magic gear effects and attack roll bonuses or damage. AoE spells are doing more damage than many single target spells.