Illusionist Thief?

[maximumride36]

So I'm going to be joining a new game soon and I wanted to see if I could be something that, even if it's not optimized, it's fun. I though mixing the rogue's thief and the wizard's illusionist could be interesting, but I'm not entire sure where to start with it. Any advice is appreciated :D

[Varlon]

First thing that came to mind - forest gnome. The flavor is appropriate, DEX and INT boosts are convenient, and you get minor illusion for free. Unless you specifically want the Thief subclass, you can go Arcane Trickster for invisible Mage Hand shenanigans and some illusion/enchantment spells. You can then start taking Wizard levels; this would get you 2nd-level spells at level 6, as compared to Arcane Trickster 7.

I love Thief and play one, but they seem more item-focused than I picture a tricky caster to be. Arcane Trickster 3/Illusion Wizard X sounds really nice to me; at character level 5 you have 8 cantrips, 11 spells known, and 5 3 1st-level slots, with super-powered versions of both mage hand and minor illusion. Combined with the extra proficiencies, Expertise, and Cunning Action from Rogue, that's a whole lot of utility and trickery to play with.

If anything that might be too "optimized", but if you did want a magic-y Thief note that they get Use Magic Device at 13th level.

[RSP]

I love Thief and play one, but they seem more item-focused than I picture a tricky caster to be. Arcane Trickster 3/Illusion Wizard X sounds really nice to me; at character level 5 you have 8 cantrips, 11 spells known, and 5 1st-level slots, with super-powered versions of both mage hand and minor illusion. Combined with the extra proficiencies, Expertise, and Cunning Action from Rogue, that's a whole lot of utility and trickery to play with.

Just curious: how do you have 5 1st level slots?

[Varlon]

Oh I knew something was wrong with one of those numbers, I was adding them together from the two classes. Just 3 slots then (though Orcpub is saying that would be a 3rd-level caster with 4 1st-level slots and 2 2nd-level slots - either this is incorrect, or Arcane Trickster counts as a 1st-level caster at minimum for multiclassing purposes even though the PHB says you divide your level by 3 and round down), but still an impressive number of cantrips and spells available.

[DarkKnightJin]

Oh I knew something was wrong with one of those numbers, I was adding them together from the two classes. Just 3 slots then (though Orcpub is saying that would be a 3rd-level caster with 4 1st-level slots and 2 2nd-level slots - either this is incorrect, or Arcane Trickster counts as a 1st-level caster at minimum for multiclassing purposes even though the PHB says you divide your level by 3 and round down), but still an impressive number of cantrips and spells available.

Since Arcane Trickster becomes a Caster at 3rd level, it will add at least 1 caster level to the Multiclass Caster chart in Chapter 6 of the PHB.

So, AT3/Wiz2 would count as a 3rd level caster in terms of available spell slots.
You still know/prepare spells as if you were a single classed caster of each type, using its spell table.
So, while you might have 2nd level slots, you won't have any 2 level spells to use them with just yet.

[Kobard]

To be a thief, you only really need an appropriate background, preferrably one with access to thieves' tools: e.g., charlatan, criminal, urchin, etc.

From there? To be an illusionist "thief", your best options are probably Illusionist Wizard, Arcane Trickster, or even Bard. It depends on where you want your character's emphasis.