Mythos/Marksman

Tinker
Tinker affects both flintlocks and rifles.
 * Passive
 * Description: "Modifications to your firearm provides it with an increased refire rate."

Piercing Barrage

 * Requires: Rifle.
 * Description: "A drilltip provides your ammunition with the ability to pierce targets, striking multiple foes in succession."

Rapid Re-fire
Increased rifle attack rate, increased damage, increased range. Costs mana per shot.
 * Requires: Rifle.
 * Description: "An ingenious rifle cartridge allows you to continuously discharge your firearm without reloading."

Black Powder

 * Passive
 * Description: "Careful adjustment to your firearm yields improved range."

Seeking Shot
Note that the mana cost and cooldown never changes.
 * Requires: Rifle.
 * Description: "You augment your ordinance to seek foes and deliver Electrical Damage using your rifle."

Rally

 * Description: "Quickly destroying monsters in succession improves your morale, augmenting your ability to attack and defend."

Glancing Barrage
Glancing Barrage modifies and builds off of Piercing Barrage.
 * Passive
 * Requires: Piercing Barrage and a Rifle.
 * Description: "Further modification allows Piercing Barrage to ricochet off of obstructions and walls, and provides the additional ability to inflict Poison on targets."

Stunning Refire
Stunning Refire builds off of Rapid Refire.
 * Passive
 * Requires: Rapid Refire and a Rifle.
 * Description: "Additional modification gives your ordinance the ability to stun targets on impact."

Napalm
Receives bonuses from Wildfire and Blistering Heat.
 * Requires: Rifle.
 * Description: "You modify your ordinance, causing your rifle shots to mercilessly burn your foes, engulfing them in flames. Nearby foes are affected by the sheer heat of the fire."

Deafening Explosion
Deafening Explosion is an AOE attack. It is modified and complimented by Ringing Ears.
 * Requires: Rifle.
 * Description: "Using your rifle you shoot an explosive round so loud it physically damages nearby foes."

Suppressive Fire

 * Passive
 * Requires: Seeking Shot and a Rifle.
 * Description: "Further tinkering gives your ammunition the ability to stun targets on impact, using your rifle."

Critical Modifications

 * Passive
 * Requires: Tinker and a Rifle.
 * Description: "Further investigation reveals opportunities for improvement. Modification improves the chance of Critical Strikes, and improves rate of fire."

Insight
Insight modifies and builds off of Rally.
 * Requires: Rally.
 * Description: "You discover the weak points of your foes with each strike, improving your chance of inflicting Critical Strikes."

Shattering Tips
Shattering Tips modifies and builds off of Piercing Barrage.
 * Passive
 * Requires: Piercing Barrage and a Rifle.
 * Description: "On impact, Piercing Barrage will shatter into blindingly fast bits of shrapnel."

Wildfire

 * Requires: Napalm and a Rifle.
 * Description: "Tendrils of flame ignite nearby foes burned by Napalm strikes."

Ringing Ears
Ringing ears modifies and builds off of Deafening Explosion.
 * Passive
 * Requires: Deafening Explosion and a Rifle.
 * Description: "''Increased decibels inflict even more damage, and may stun enemies who succumb to the sound.

Penetrating Fire
Penetrating Fire modifies and builds off of Seeking Shot.
 * Passive
 * Requires: Seeking Shot and a Rifle.
 * Description: "Refinement provides further damage bonuses, and allows you to refire Seeking Shots more readily."

Marksman's Refire
Marksman's Refire modifies Rapid Refire.
 * Passive
 * Requires: Rapid Refire and a Rifle.
 * Description: "Refinements to your design improve the efficiency and deadliness of Rapid Refire."

Blistering Heat

 * Passive
 * Requires: Napalm and a Rifle.
 * Description: "A highly improved version of Napalm."

Note that "‡" denotes an unverified value.