Splodey Darts causes certain projectiles to explode when they expire (from running out of pierce, reaching the end of their lifespan, hitting an immune Bloon, hitting a line of sight blocker, etc). For Max, it applies to his regular darts and Dartnado darts, but not when Bullseye is active. For Juggernaut Max, it only applies to his default attack, not Keep Rolling or Spiky Chaos. The explosion deals 1 explosion-typedamage and has 8 pierce. It can hit Camo Bloons even if the thrower does not have Camo detection. Its base damage and pierce cannot be increased, but it does inherit other modifiers from buffs and trinkets (increased blast radius, added status effects, damage bonuses against specific Bloons, etc).
Due to both Max variants relying more on attack speed than damage for the best damage output, this weapon is arguably the best in slot for both of them, potentially outpacing the damage buff from Lightning Bolts.