I like the arenas you have right now but I would like to see a rebranding of them along with some new ones along with unique head of each one. Carina will want to keep the GrandMaster and Collector from getting in the way for her plans. Why not put the Collector in charge of One character Arena and GrandMaster in charge of the second?? We also have the Teir one Alpha, catalyst clash, and teir 4 catalyst arenas. Chose some of the other Elders of the Universe to rule over those competitions?? Here is a list...
https://comicvine.gamespot.com/elders-of-the-universe/4060-41142/characters/So put the Champion in charge of Catalyst clash. The Possessor could run the alpha and tier 4 . Then we also need some new ones. How about one for potions run by the caregiver?? a gold or unit arena could be run by the Profiteer?