Very deserved such whacks too, I might add.
1) move up any killer features above the first two levels. Once you reach level 3, you will have access to everything that was in the UA, but others can no longer cherry pick just a single level. Once you decide to invest three levels of a class, you're immediately confronted with the tough choice to invest a fourth (for the ASI) and a fifth (for the Extra Attack)... and by that time, the excellent MC rules of 5E will have claimed another victory!
2) clarify what the invisible to darkness malarky really means
3) clarify a few details about how multiclassing affects beast features and the interaction between beast "extra attack" (not its name) and character extra attack