If you like Peri more I'd suggest building her, for a crazy lady she is kind of fun. That said 30 Res is a bit low for Ploys, but you could give her Atk Smoke.
True I wasn't factoring in Fury, but I generally like 35 as a baseline for running Ploys. Could run Atk smoke in the C and Def Ploy in the S, that might work well enough, and if it's not reliable easy to swap out for something else.
If you like Peri more then you should just promote her first. The game is more enjoyable if you promote the units that you like more, and you use her more so that’s extra reason
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