Alpha Disruptor
The Alpha Disruptor was one of the last weapons you picked up in Tools of Destruction, but here you can purchase it from the Smuggler on the beach of Hoolefar Island. You will need 50,000 bolts, and it becomes available after defending the island from the undead pirates.
Pyrocidic Precipitation
After rescuing Talwyn--which is optional, but gives you access to the first weapon modification--you'll find a stack of metal crates near the exit. Save a Fusion Grenade for these crates, because hidden in one of them is a mod for the Combustor. The Pyrocidic Precipitation mod makes the shots fired drip onto the floor to cause damage to your enemies.
Concussion Detonators and Voltage Multiplier
In the bay in Hoolefar island, there's a hidden, underwater cave. Search through it and you'll find some more mods. Swim into the cave, then break open the gate with a Fusion Grenade. Take a Helio Grub into the next room, where you'll find the Concussion Detonators. These add knockback to the grenades, so enemies who aren't blown up will be thrown back by your bombs. Blow up the next gate and climb the ledge. You'll discover another mod: Voltage Multiplier. This makes the electricity from your Lightning Ravager arc from enemy to enemy, causing more damage.
Gyro-Turbine
When you arrive at Darkwater Cove, before you begin solving the first riddle, you'll have the chance to find another mod. Before taking the Spring Pad, jump up and over the netting. You'll find some more platforms that you can climb up to discover this mod. It makes your tornadoes from the Tornado Launcher last longer, causing more damage.
Zero-Kelvin Laser Diode
After defeating the Pythor, grab another Helio Grub and head left. Smash the crates and carefully cross the platforms. You'll find this mod, which makes the laser freeze enemies on contact.
Dual-Targeting Lasers
Continue from the area where you defeated the Pythor until you discover a Pirate Door to the left. You can blow this up with a Fusion Grenade, then blow up the metal crates inside, revealing a Jump Pad. Take this pad for the Predator Launcher mod: Dual-Targeting Lasers. Each target point will have two missiles locked on: double the fun, double the damage.
Anti-Matter Transfluxor
After rescuing Talwyn from the pirate ships, head to the end of the deck. Climb up the crates, slide down the zip line and turn around to find the final mod. The Anti-Matter Transfluxor makes your Alpha Cannon fire through enemies, damaging anyone who happens to be behind the first target.