So your first time trying to fight Wrex you (well, I certainly did) are probably gonna get overwhelmed by all the high-level spells getting tossed around, so you might equip some Reflect Rings (or just cast Reflect).
That's when Wrexsoul is likely to be the arbiter of his own demise by reflecting Rasp back onto himself, stunning him. With the right team (luckily I had Celes and Edgar), it's pretty easy to just stunlock him to death.
Nice design ![]()