>>96498422
Mirror image and Blur seem good on paper, but considering most fights last 3 rounds tops, spending one of them to just defensively buff up when you are a ranged character ie already out of harms way and could sneak around with your bonus action instead it's not great pick. Blur is just straight up worse than Mirror image imo. Shield can be done on reaction at any time you get swarmed by enemies to give you a freakish ac just when you need it, without using any of your precious few actions.

Your reasoning on misty step is sound, it's nice to have, but with your limited slots and your cunning action you can probably do without it.

As someone who seems very preoccupied with defensive stuff in a deadly game, consider Fog cloud. An often forgotten trait of these spells that obscure vision is that attacks of opportunity cannot be made on targets that cannot be seen. Meaning you could bail a fellow player out if they're getting attacked by putting a fog cloud on them, allowing them to run out of there as if they had disengaged. Invisibility can achieve the same thing, but is only touch range, so more for yourself in most situations, and then you can just bonus action disengage.

If you have access to a feat, and you get to use Tasha's cauldron for everything, consider picking up the Metamagic Adept feat. Subtle and Quicken. Casting spells completely silently while sneaking around or in plain sight when talking to npcs without any indication it was you could really up the trickery feel of your character and would probably be really fun. With quicken you could also potentially pick up something like Hold person and fish for an auto-crit where you bonus cast the hold person and sneak attack crit them on the same turn if it lands. You could only do it once per long rest and it's not the best, but would feel really cool.