I just got smacked by the collector chapter 2

Read the caption, looking for tips first time fighting him should i just try and study his specials and dex them or should I level the right Champs and wait to slay him from once he came . I'm really looking forward to these upgraded reward. im not a super long time player but i know people beat him with like 2 stars or f-ing or a couple 3 stars and like 2 4 stars so idk I'm not super good at the game