Plank

25%/30%/40%/50% chance to explode on hit

Unlock: Available from the start
Starting weapon for: 31 characters

Community builds that use it

ApprenticeLevel-ups give every damage stat, so hybrid weapons pay off: Plank, Lightning Shiv and Cacti Club, or SMG/Double Barrel Shotgun and Slingshot for ranged. Take Luck to reach the higher Max HP level-ups.
ArtificerExplosion build: start Shredder and move to Rocket, Grenade or Nuclear Launchers, or use Planks; stack Explosion Size and Elemental Damage, which also enlarges explosions. Wrench and Screwdriver became viable after Tool weapons got +100% damage in 1.1.0.0.
CyborgKeep the Minigun, add guns that scale with Ranged Damage and Engineering weapons (Wrench or Plank), and put upgrades into Ranged Damage rather than Engineering, since Ranged Damage converts to Engineering mid-wave.
GluttonSix Pruners spawn Gardens whose consumables trigger Glutton's explosions; stack Luck and Melee Damage and stay at full HP so each pickup adds Explosion Damage. Spicy Sauce merges into the innate explosion, and Lemonade or Weird Food help heal.
TechnomageEngineering with Wrench turrets is the reported easier route after the XP nerf, while elemental builds use Taser or Plank and buy every structure. Strange Book converts Elemental Damage to Engineering.

Stats by tier

Tier I Common
Damage
10 (+60% Melee Damage, +60% Elemental Damage, +60% Engineering)
Cooldown
1.23s
Crit
x2 (3% chance)
Range
150
Tier II Uncommon
Damage
15 (+70% Melee Damage, +70% Elemental Damage, +70% Engineering)
Cooldown
1.14s
Crit
x2 (3% chance)
Range
150
Tier III Rare
Damage
20 (+80% Melee Damage, +80% Elemental Damage, +80% Engineering)
Cooldown
1.06s
Crit
x2 (3% chance)
Range
150
Tier IV Legendary
Damage
30 (+90% Melee Damage, +90% Elemental Damage, +90% Engineering)
Cooldown
0.98s
Crit
x2 (3% chance)
Range
150

Damage in brackets is added from your stats before %Damage multiplies the total; see the damage formula or the calculator.

DPS at tier IV

31.5 DPS with no stats, 50.4 at 20 Melee Damage and 78.8 at 50 (single target, every projectile hits, crits averaged): #41 of 58 weapons that scale with Melee Damage. Full ranking or your own stats.