Here are a few of my builds. In my opinion (as a charger main), the
only ability you actually need on a charger is swim speed. Every other ability choice is just making things easier
to the point where you don't need to be as good at the main weapon. This aside, some of the best other abilities are going to be special-related abilities, and a sub or a few subs of qsj. I'm not really one to make builds for map/mode combos, so the different builds I post will be in chronological order of when I used them (top being the one I use now)
Haunt gang
o
Back when I ran ISM
Okay looking back there's a bunch of older builds I had which ran more special charge or ink recov and ism and swim. Anyways, I realize haunt isn't everyone's cup of tea, so if you don't like it, some run respawn punisher. You could run more swim speed, or special abilities or whatever fits your playstyle really.
Something I want to talk about before I hit post is the "controversy" of running ism (ink saver main). I don't. Even on E-Liter where you only get 4 shots. Here's why. Any charger player should practice shooting to kill, not shooting becuase you have have a full charge. Getting into the habit of cancelling charges when there's no point in shooting will prove to be beneficial for a few reasons. First, when you have your laser out all the time, people will actively try to avoid you. Let's say someone is swimming back to mid, and as they're going, they see a charger shot paint near where they're going. They're gonna be more cautious. Had you waited to shoot until you had a shot, you would've gotten the kill. Also if you shoot all the time you're gonna be struggling with ink consumption and will waste ability slots that encourage poor play. Cancelling charges when you don't have a shot or are gonna die before full charge is also useful because it allows you to reposition more often into better, more sneaky or safe spots to charge up and then take your shot. I've come to this reasoning after discussing with other competitive charger mains and pondering it myself, and challenging myself to not run any ism. Anyways, I wish you good luck and happy sniping!