The Handcannon is a single shot projectile weapon in Disfigure. It has the highest possible bullet damage and size, the second lowest fire rate, and the third highest bullet speed.

For its perks, the entire left side of the possible perks all synergise with different upgrades, the middle all damage based perks, and the right fire rate (except the last, it nerfs fire rate for more bullets fired per shot.)

Nearly every upgrade scales with bullet damage, some that don't actually gain it later on (looking at you, rockets). Higher base bullet damage also buffs possible damage upgrades since each one is a percentage increase of your base bullet damage. E.g. 50% extra bullet damage = 20 extra damage, 100% = 40 extra damage, 300% = 1200 extra damage (base handcannon damage is 40).

Upgrades that can sustain themselves off of other means such as 'Plasma Ball', 'Calypso', 'Spikes', 'Meteor', and 'Trail' all work best with Handcannon because of their self-sustainability, since only the bullet damage stat matters to get them to work.

Passive upgrades such as 'Light Target' and 'Cone Vision' also work very well with Handcannon since both upgrade bullet damage when criteria is met, and Handcannon has the highest base damage to multiply.

Firing based upgrades such as 'Missiles', 'Radiation', and 'Flashbangs' aren't as particularly powerful because of the significantly low fire rate the Handcannon has, but it can be supplemented by upgrades such as 'Wild Strikes' and 'Ricochet Rounds'... as long as you don't miss.

Despite its shortcomings, most if not all of them can be supplimented by upgrades. Because it has really high stats (except fire rate) there isn't many shortcomings at all!

Simply put, the Handcannon can do nearly everything other builds can do, but better.

No bullet damage runs: Best with Handcannon (These ones are honestly always absurdly overpowered
High firerate runs: Best with Minigun
Only bullet damage runs: Best with Handcannon
One shot clears the screen runs: Best with Greatsword (Handcannon takes the second spot)
Testing new upgrades: Handcannon (I've noticed that handcannon is typically the best choice no matter what)
Highest possible damage numbers: Handcannon again!
One shot runs: Handcannon
Biggest bullets possible: Greatsword (Handcannon and Sniper take second place because the slash attack of greatsword is just larger)
All upgrade no bullet run: Handcannon

You can also use the handcannon as a panic button when something gets too close because of how much damage it can do on a good day.

Handcannon is just really really boring.

Its a really basic weapon with the only caveat of not being able to pierce (Countered by ricochet but whatever).

Other weapons have fun little quirks that you can play with such as Twin Katana's 'Sakura' build (so many attacks around the character at all times that it looks like a flower of death) or Saw Launcher's 'Cloud of Blades' build (Oops all saw!) that make them interesting to play with. However, unlike the Handcannon, they're all significantly more niche and sometimes harder to get started with.

Handcannon just pairs well with almost all upgrades, and that makes it versatile. Use it for easy wins or to test the viability of new upgrades or builds. But if you want something more niche, use something more unique.

Aight. I call this one: 'Calypsooo'

In the build your main method of attack will be Calypso. Calypso is extremely high fire rate so you should definitely use Bleed and Electricity to pair with it. Since it scales with bullet damage and bullet speed, you should also use Bulk Rounds to upgrade it as much as you can (Winding strikes got buffed in Colossus Part 2 so it synergises with any bullet damage scaling upgrade too).
For slowdown, I recommend specialising in freezing your enemies rather than just slowing them down. If that doesn't work then slowdown will be fine.

Most of the time Calypso will actually one shot grunts if you upgrade your damage enough and eventually delete minibosses before the Calypso projectiles disappear. Your toughest opponents will be the bosses, because if you aren't careful your Calypso will run out and you'll be left with a butchered Handcannon that'll fire after 200 years pass. The bosses will also disintegrate quickly with all Calypso projectiles on them, but maintaining them all is what makes that tough.