Demoman Driller (EXPLOSIONS!!!!!!!!!!!!)

Perks I use: Dash, IW, Vampire, Resupplier, Deep Pockets(i like money)

This build is just loads of explosions lmao, more for the fun of explosions than anything meta-breaking but i still genuinely consider it viable and use it everywhere

Sludge pump's Volatile Impact Mixture has decent single target while still retaining crowd control with charged shots. Your crowd control comes from very liberal use of every explosive in your arsenal. With the Sludge Pump either carelly lead single shots on targets without missing for ammo conservation or Hail Mary mag dump on beefy targets, whatever floats your boat.

The EPC is RnD's gift to dwarfkind and does everything you could ask for. On top of EPC mining Thin Containment Field explosions also pack a punch. I over-specialise by putting on Overcharger OC, gives me even more explosions with charged shots. Note that TCF explosions are strictly superior in both damage and radius to Overcharger shots, but I still like it to take out clumps of grunts when I'm not in a position to stand perfectly still and line up a TCF. Overcharger also grants you a little extra long range capability on stationary targets like Sniper Turrets and Vartok nodules. I prioritise using the EPC for mining over explosion kills and you only have so much EPC ammo, which is where HE grenades come in.

. I have a lot of fun with HE grenades. Basically treat them as a mini C4. You can see how long a grenade has been "cooking" by a circular bar next to your crosshair when you hold the button down. Theres a bit of a learning curve with the fuse timing and the bounce/roll but once you figure it out you can kill a lot of things. Most notably you can bl0w up clusters of bugs from distances you wouldn't normally be able to reach, and since it detonates on a timer and not on impact you can airburst it to kill Mactera, Naedocytes (i hate naedocytes) and Swarmer Drones. You can also arch it to kill bugs on ledges above you or airburst it on bugs on the walls. The distance you can throw grenades makes it unique to C4. Even with its medium range capabilities you're still free to bl0w up chunks of bugs two feet away from you. Note that like C4, a grenade will one-shot you and teammates in the blast radius. It'll oneshot Grunts and Slashers but not Guards, though anything that survives is feared with armour broken so thats nice. Overall HE grenades are really fun to bl0w stuff up with to save Sludge and EPC ammo, if you get jumped by some bugs Dash away while cooking then turn around and bl0w them to kingdom come.

Melee kills with Drills are a key component to how I play Driller since you lose out on the healing of Axes. You need to run 1111 or 1112 if you wanna kill anything without taking half an hour. Use your drills to capitalise on singular or groups of Grunts and Slashers for healing with Vampire. Drilling clumps of bugs will hurt and inflict Stun/Fear on all of them, so don't worry about getting bit too hard. Toss in power attacks whenever you have them to keep your health topped up. As is the nature of explosions, you're gonna need at least the slightest bit of distance between you and bugs if you don't want to self-damage. Your Drills have no such weakness so use them in a pinch to Stun/Fear anything in your face. Also use your Drills on Naedocytes it just works.

To complete the explosions galore build, remember to use your C4 just as liberally to gloriously eviserate even bigger swarms of bugs than your HE grenade can handle, as every Driller should. One trick I learned from Reddit is throwing your C4 into the air and immediately throwing a flare to make it stick midair, giving you some more vertical coverage.

As an additional tip, You can abuse the 3/6 seconds of invincibility a dwarf has when they're revived to revive a teammate while under IW, then immediately drop C4 and bl0w up all the bugs at were biting their dead body while you're both invincible. You can also do this vice versa if you're the one being revived by an IW'd guy.

Use Dash to transfer yourself from a position where you are surrounded to a positon where the entire swarm is coming at you from one direction that you're free to lob grenades at. Dash saves my life every single day.

Fun fact, karl gg's profanity filter blocks the word "bl0w", wasting twenty minutes of my life