Terraxia was the female Thanos that Thanos with the IG made during his battle with the heroes, right? Well, due to her only being around a very limited time, I dont think feats are going to win her any battles, BUT considering the MASSIVE POWER that Thanos had with the IG, even if he made her .0000001% of his own power, shed probably be a match for Gladiator. So theres no real way to prove it, but chances are Terraxia is certainly in High Herald level (especially if she ripped Iron Mans head off in minutes).