-Your weapon pierces multiple enemies with its damage reduced for each enemy it hits (useless for weapons that innately pierce/ignore collision though, unless we do it like charged shot, which...)
-Additional effect for weapons that innately pierce like Vortex/Railgun (less damage reduction from hitting multiple enemies, might be bad or need balancing on vortex though)
-Bypass enemy shields / deal more damage to enemy hull when enemy is shielded (i know there's only one enemy that shields right now, but with Enemies 2.0, maybe more shielded enemies+ a "Shielder" enemy (instead/in addition to the i-think-already-planned "Healer") could make this useful. We need stronger enemy shields or more shielding enemies which other people have suggested and designed.
maybe additional mods (If it's going to be a tree) are:
1. Reduce damage reduction on subsequent enemies
2. Boost damage on subsequent enemies
3. Final mod being Weapons bounce once on the edge of the screen.