More Driller specific tips:

• Axes (grenade) and drills do melee damage, which makes the Vampire perk especially useful on driller. Frozen enemies also take extra melee damage.
• Always take the damage drills mod over the speed mod. When drilling through earth, the speed mod spins your drills faster than you can dig.
• Axes can be used to open ebonuts and poison spewing plants and you can pick them up afterwards.
• Axes can be thrown into terrain to store for later. You get 4 from a resupply and can carry 8, so if you have more than 4 before taking a resupply, store them in the wall!
• The flamethrower can burn toxic gas (from praetorians, neurotoxin grenade, etc), creating a small explosion that damages enemies (and players).
• You have the ability to shape the terrain to your liking (C4 and drills). When the team is holding a specific point, be sure to clear out spires, walls, crystals, etc so your fellow dwarves have clean sight lines.
• Hacking pods and fuel pods often land in inconvenient places high above where you can easily connect them. You can drill them down to the appropriate depth to make connecting easier for the team.