One of the major additions in the Sisters of Parvos update (U30.5) was a new series of mods called Galvanized mods. These mods are one part of the "Arsenal Divide" section of the update, intended to reduce the power gap between Melee and ranged weapons. The Galvanized mods are all variants of existing mods, with slightly reduced base stats but a ramp-up mechanic that drastically increases their power upon kills.
These mods are all available from the Arbitration Store, for 20 Vitus Essence each. They are all Rank 10 mods, with the rank-up costs of a Rare (Gold) mod.
EDIT 12/11/2021: DE have clarified in U30.9 that the +Damage from Galv Apt/Shot/Savvy not working on explosions is intended.