Chargers are pretty poor creatures when unupped. Things you could consider trying instead/in addition:
-Otyughs (great synergy with armor and easy CC on most things that don't get caught by gravity shield)
-A catapult or two of your own (so you can spam a few BBs on your own creature late-game and then fling it for a killing blow - if you choose this, I'd probably say add more BBs, possibly replacing some/all of the armors)
-Acceleration (so you can substantially boost your own damage, and then keep your accel'd creature alive with more armors)
If you go with either the catapult option or the acceleration option, I would probably recommend replacing all six chargers with six armagios, since they're great catapult/accel targets, and their built-in gpull can be used to stall while you're setting up. If you go with otys, only do a few otys, and maybe add shriekers or something else that's pretty hard-hitting to do your actual damage. Oty option is probably the least effective option of the three I listed, but it's also the most thematically appropriate option.
FWIW you're probably not going to hit the point of top-tier deck with this strategy, but you should definitely be able to put something together that will work well enough in pvp1, ai3, and maybe even ai4/bronze.