Launcher Mastery card lets you reload the Boomshot, Dropshot and Torque Bow faster. Their active reload bar on grey and white are bigger, more chance of landing. And slightly faster to reload by split second, especially when perfect active reload bar not available because of cooldown (no white bar yet). Also, the white perfect active reload bar is increased in size.
Custom Lancer GL card lets you do bigger damage with GL’s explosive rounds and bullets. You can increase it further by using Critical Damage and Assault Rifle Damage Perks. Even headshots with bullets are great to do, on the weaker enemies or early waves. The difference between non-active GL and perfect active Custom GL is doubled damaged. There are times when you’d drop a normal GL round on a Drone’s head and it’ll just get downed. But… if you drop a perfect active reloaded Custom GL on their head, they’ll flat out die. Bypassed execution rules. And the Custom GL on perfect active reloaded is INSANE on Bosses. Perfect active reload once and fire multiple rounds. In fact now, I try to perfect active whenever I can and usually reserve one round per enemy or clusters.
Custom Boomshot is better too since when you shoot normal Boomshot around Wave 41+ on Master, it won’t destroy Bastion’s shield in one normal shot. Even perfect active reload may not. But… if you had Custom Boomshot, perfect active reload on that will one shot a Bastion shield on Wave 41+ Master,
I personally use Razor Hail, Custom Lancer GL, Custo, Boomshot, Launcher Capacity and Officer’s Prerogative.
Pro tip, when you are fighting Bosses like Kestrel, Matriarch, Snatcher or Carrier, if you perfect active reload your Custom Boomshot or Custom GL, then use your Ult on Boss. The perfect active reload damage bonus will carry over to your Ultimate, and could potentially one shot. It’s really much bigger damage. They could die in seconds on Wave 40 and 50 on Master. Perfect active reload Ult + Custom GL rounds together.
Another pro tip, if there are two Wardens, two Stumps or two Sentinels next to each other. Basically, any Mini-Bosses or Bosses close to each other like it can happen on Horde Frenzy too, it is the perfect opportunity to drop Officer’s Prerogative. It will deal damage to both enemies. Kill two birds with one stone. But it would require patience and timing under pressure.