Mimic

Today, you've armed yourself with a variety of weapons to face anyone who wants to test your mettle. Of course, there were plenty of those looking for "free" kills, some serious and worthy, but as you've probably guessed, you defeated them all.
While wandering around these places, looking for another volunteer, you came across a strange Reitraxian, his stance challenging you to battle. Naturally, this strangeness caught your attention, but you decided to ignore it and ran after him. At that moment, he also ran, leading the way.
You arrived at his location, already energized and ready for battle. You expected it to be an easy fight, as these Reitraxian types are very weak to you, so... Free kill! Well, you rushed him first, and he rushed you, and a battle of claws and metal began.
Unfortunately, the entire battle unfolded with such suddenness that your entire weapon was destroyed and you were knocked to the floor. It seemed impossible for such a weak Reitraxian to possess such strength! He placed his foot on your body, gently and triumphantly propping himself up, and fixed you with a menacing gaze. Then, in an instant, he shed that feeble form, assuming his true form. Now the deception was clear. A mimic.