Sometimes, you need to be the size of a Sprite and sneak into places you shouldn't be... and other times you need to be able to stand toe to toe with a Frost Giant. If you're Ant-Man, you might need to do both during the same adventure... and with this build, you can!

The build is inspired by the MCU's Scott Lang version of Ant-Man. We want to be a thief who can change size, going from Tiny to Huge, while also using ants to pull off a lot of his schemes.

We really fulfill most of our big (pun intended) goals on this build at level 11, with a few more of the slightly flavorful bits at level 14. After that, there's six levels you could use to customize as you choose.

Our Race choice for Ant-Man is any Small race, but one stands out: Forest Gnome, who can speak to Small or smaller beasts... like Ants. A high Dexterity is the only ability score we desperately want, while a good Intelligence is also desirable. Whether you're using the Tasha's variant ability scores or not, Forest Gnome matches up very well here, and you can start with a 16 in both scores using the standard array. One other option would be the Variant Lineage to get Eldritch Adept, and use that for Beast Speech.

We'll start out as a Rogue. I'd recommend Expertise in Stealth and Sleight of Hand. For our background, Criminal obviously is a great fit, as is Charlatan. Both Arcana and Animal Handling can be useful skills to add in through your background.

Level 2 gets us Cunning Action.

At level 3, we want to go with Arcane Trickster. We'll obviously be learning Mage Hand, and I'd recommend Booming Blade if you're concerned about getting the most damage. Infestation is a remarkably thematic choice, if not on the same level power-wise. Message lets you talk to creatures - INCLUDING ANTS - at a distance. For our first level spells, Find Familiar is obviously excellent from a practical standpoint and thematic, if you can describe it as an ant instead of a spider. Shield is also a great choice - you temporarily shrink down to avoid a hit before popping back up to full size. Disguise Self and Charm Person are always useful picks - they aren't exactly Ant-Man staples, but there's not a lot else to take for 1st level Enchantments and Illusions.

At level 4, we get our first Ability Score increase. Personally, I like taking Squat Nimbleness to get your speed up to 30, with Athlete also making a lot of sense. You could, of course, just go for 2 Dexterity. Silent Image is a great utility pick for your new spell.

Levels 5 and 6 we don't make many choices, save for Expertise in two extra skills. Expertise in Animal Handling at this point could be a nice fit, if you picked it up with your background, while Athletics and Acrobatics also make a lot of sense. At level 7 you get your first 2nd level spell - Invisibility seems good. Just explain it as shrinking yourself down to Ant size for a few moments.

Level 8, we get another ASI/Feat. I'd either take the feat you DIDN't take last time (so you now have Athlete and Squat Nimbleness) OR another 2 Dexterity - this should put you at either 20 or 18 Dexterity. But even more important, we can learn a 2nd level spell that is NOT Enchantment or Illusion. We're going to take Enlarge/Reduce. We can now shrink down to Tiny size - the same size as a sprite or a spider. Or an ant! It's not a great combat form, but it's incredible for sneaking in and out of places. Even if you are shrunk down, you can still hit someone with a 4d6 Sneak Attack, plus Booming Blade - losing a d4 of damage isn't nothing, but it's mitigated somewhat.

At this point, we're going to switch over to Fighter. Depending on exactly how you like to fight, you might go for the Two Weapon Fighting (not with Booming Blade), Dueling or Defense fighting styles. At Fighter 2 (level 10) we grab Action Surge.

At level 11, we take our third level of Fighter, and go for Rune Knight. We want the Cloud and Fire runes here - Advantage on Sleight of Hand and Deception checks and Expertise with ALL your tool proficiencies is a pretty sweet deal. Your Fire Rune is clearly infesting your enemies with Fire Ants! Also important here, we get the Giant's Might ability, which lets us increase in size to Large. And you can cast Enlarge on yourself AFTER that, jumping up to Huge size. You are now Giant-Man!

At this point, we're in pretty good shape as Ant-Man. If you want to continue building up the theme, I recommend three levels of Ranger, going for Swarmkeeper. Your Favored Terrain and Enemy choices obviously depend on your campaign, and your new skill training depends on what you're lacking. Swarmkeeper makes your Mage Hand (which you're using for all sorts of tasks as an Arcane Trickster) appear to be made out of a swarm of insects, and your swarm of ants is also going to be biting everything you attack.

With your last six levels... completely up to you! If you've survived being Ant-Man to level 14, you should have an idea of what you need. Two good choices would be bringing Rogue up to 13 (for a Bonus Action of your Mage Hand distracting a target), or rounding your Fighter and Ranger levels up to 4 for the ASIs. If you spend all six of the remaining levels in Ranger, you can get Gaseous Form, which can be useful for getting in to locked doors if your DM doesn't want to let "Tiny" be small enough for that.

Overall, you'll play similar to any Arcane Trickster in combat for the first half of your career, while later focusing on becoming very big in fights to hit things harder while taking up a large portion of the battlefield. Most of the fun here is out of combat, being able to sneak in to places you normally couldn't.