If an Evie is coming after you solo, gather around with enemies to avoid being out-flanked. Also, expect an Evie after ice-block to teleport immediately.
Lex is a flank champion, yes but he has a very restricted movement, and he can't move vertically, so he's easy to spot and easy to predict where he's coming from.
so get to a high ground, mine the entrance, and you should always have the upper hand.