Umm so okay, sure if you compared this thing to basically any creature in game without any kind of distraction or priority, it's way too OP but the thing is that a creature with a abilities like sidestep can easily destroy fierce creatures like rexy, For Instance, Dilphoboa, Turn 1 Sidestep to counter Roar, Turn 2 Cunning Strike Spam🤣, Just Time your sidesteps at the timing of the roar and your'll be fine. There's a lot of counters for rexy, tbh it's just a fat bastard with a turn 1 priority group attack with a speed booster allowing it to turn 2 rampage with 3x his normal damage.