Drone Piercer
Drone Piercer is an Isaac artifact that gives all your drones' attacks pierce each turn.
Strategy
This artifact, like many pierce sources, has some incidental value in some fights - kill Needler and a few other specific enemies easily, not have to worry about Armor or Temp Shield on enemies, etc. This is slightly better than usual on drones, that are usually a bit harder to position than your Cannons because of Droneshift's relative scarcity.
Pierce is a very self-synergistic mechanic - it's at its best when all of your attacks pierce, so that your enemy's Shield doesn't matter. (On the other hand, a mix of piercing and non-piercing attacks isn't any better than all non-piercing in most fights, since your enemy's Shield will still find use in blocking your non-piercing shots). So that makes this artifact at its best on ships that are doing most of their damage through drones - Drone Piercer will apply to most/all of your damage and essentially negate your enemy's shield. It also means that it's very good with Piercer as that allows you to mix in some offense from your own ship and still be attacking with mostly piercing things. It can also be good with Drake on your crew if you've drafted a few piercing cards, as you can play those alongside your piercing drone attacks. Dizzy's Corrosion-based builds can work well with this too, as corrosion damage natively pierces.
Note that Jupiter Drones' attacks all gain pierce with this artifact even if the original attack did not. In ordinary circumstances, this can actually be underwhelming most of the time since builds with Jupiter Drones tend to also want to be attacking the enemy ship with their own cannons a lot, meaning enemy Shield will still find use in blocking your main cannons unless you have ways to make that pierce too.
But for the Jupiter, all your offense is coming from Jupiter Drones, making this artifact an amazing pickup for that ship specifically - instantly rendering all enemy Shield for the rest of the run completely moot, with no effort on your part.