While a lot of the experience through Baldur’s Gate 3 is as a fighting monsters tactical game, there are a surprising amount of magic that can in fact happen outside of combat for the heritage of game I was used to.
in my opinion, most subclasses of wizards underperform in tactical compared to the other arcane casters, but they can be perfectly capable. Even then, wizards just are not top caster.
As an illusion specialist wizard, their subclass benefits in combat are of more niche benefit than Abjuration of Evocation. For a stealth-style game, minor illusion will really aid in sneaking, pickpocketing, getting past doors that are watched, unlocking what is in public. The 2nd level illusionist benefit around minor illusion allows casting minor illusion while hidden and silenced. However minor illusion scrolls are abundant, so anyone can cast them. How often will you find yourself silenced or needing to stay hidden? I did not find my casters being hit with silence a lot, and I found that I could break the group and have another character engage dialog with the NPC in order to make them change facing so my stealth character could get in behind them to open a door or pickpocket.
Disguise self, I’m told, can change dialog options offered so that might have some value for you! Again, disguise self scrolls are going to be pretty common, and any class can cast from a scroll.
Brewing potions of invisibility is something that can be done as your party finds ingredients. Anyone can brew potions, although transmuter wizards have a chance to double potion output if they do the alchemy.
in the end, the diminished spell availability kinda makes the Wizard class not the top caster like they can be in table top (I’m not saying they are terrible), and the illusion spells that are in the game can be okay but there is no DM to get creative with things.
