No-one currently, although used to serve Blackout before he was separated from Darkmount
Standard Makuta weaknesses
Jarvis, and anyone associated with him
Makuta Ferox was one of the Makuta fighting in the Battle of Zev's HQ. He survived the battle, and was on Darkmount after for a while, working as normal.
However, he was sucked into the vacuum of space during a battle, and wasn't seen since until he appeared to Turel and Rahksha recently, behaving very... strangely. This was because he was being controlled by a device built by Jarvis. Subsequently, when Jarvis died, Ferox was freed from it's control. He proceeded to absorb most of the equipment in his lab, and fly out into space, where he saw Muta and Muta fighting. Recognizing the former as being Jarvis' creation, he engaged them in battle.