Phaedra is a large female mare colossi that meets Weed. She was made by Yveltal as part of the original colossi to guard the land, in her case it's the grave fields. Her area is a lot more lush and green then a usual colossi area. She also is more reasonable colossi compared to the other colossi who would most likely just kill. This doesn't mean she doesn't have ways to defend herself though.
Phaedra first appears when Weed enters her territory. She gets up after being hit and first listened to weed with confusion. She shakes out her orb and places it on her head, as if a challenge to see If weed can get it. She keeps stomping him back so weed keeps his distance and does the same thing to keep him inside the four chambers. But after weed shouts out the risk all the worlds are, she decides to give up her chakra orb for him, thus killing herself in order to do so.