Non team oriented players could always choose not to use it. Second player could use their combo after the first , resulting in skill chain/MB. The timing might be more difficult , but if you had enough time after the first player went (maybe 5-7 secs?) they it could be a fun addition. Certainly less button mashing and more paying attention. Maybe even mix it up with mobs that can resist or reflect the skill chain. I haven't done end game in 2.0 yet so not sure how those players feel. Would be interesting to get their opinion with how the current end game balance is (if it fits)