Arcane Trickster Mind Thrust spell clarification

Question

My first question is: am I reading correctly that Mind Thrust UA is a "2nd-level enchantment" available in the wizard spell list (i.e. the Arcane Trickster can get this spell). No one really talks about Arcane Trickster's using this so I thought it might not be available.

If it is my second question is about comparable value. When taking a lvl 2 spell within my school of limitations (illusion/enchantment) I would be turning down:

• Blur
• Invisibility (correct me if I am wrong about this being in the school of limitations)
• Mirror Image
• Shadow Blade

These are all quite formidable options. However, my toolkit is quite full of illusion spells so I am looking for more damage. Casting an attack as a bonus action, particularly (if the enemy's save fails) it means I don't have to disengage and they can't chase and attack me next turn seems quite valuable. And the fact that it deals damage even on a successful save.

At the cost of not having a more defensive spell this seems very good against low intelligence enemies. Am I A) misreading the usage of the Bonus Action or B) missing some limitation of this spell that makes it too niche?

By my calculations a simple comparison against Shadow Blade is:

• Shadow Blade casts 1d8 extra damage (over my standard Rapier); versus Mind Thrust's 3d6 damage (with a minimum of 3d6/2 damage)
• Shadow Blade allows a guaranteed disengage Bonus Action; whereas this must hit to avoid Opportunity Attacks
• Shadow Blade increases potential for SA; versus Mind Thrust's ability to not take damage next round

Answer 1

Your source is outdated

Although your Wikidot link says its description of Mind Thrust comes from the Psionic Options Revisited UA, it actually comes from an earlier UA with a less descriptive title. Mind Thrust is also described in Psionic Options Revisited, but it has several notable changes compared to the older version:

1. It has a casting time of 1 action, not 1 bonus action
2. It has a range of 90 ft, not 60 ft
3. It uses only Verbal components, not verbal and somatic
4. It is for Sorcerers and Wizards only, not Warlocks

After this second revision, the spell was released in Tasha's Cauldron of Everything as Tasha's Mind Whip, but other than the name it is identical to the revised UA Mind Thrust. If your DM allows you to use the earlier version then that's their choice, but I would say that since the spell was changed to be an action it probably was determined to be too strong as a bonus action and you are correctly reading that it would be a very appealing option. It could still be appealing since Arcane Tricksters don't get a lot of good options for damaging spells without using their very limited "any school" spells, but the revised UA and official published versions of the spell do not have the specific advantage you were expecting.