If you are struggling on 100/2 with the guide in the OP I'd recommend trying this strat instead https://www.youtube.com/watch?v=SYjkz1owBkQ

The important part being just having Prince up front early and on the field providing his buff instead of supporting Katie at the exit. Then you just need to have a decent duelist and healer, followed up with a way to deal with the ranged minions so they don't pile up on you.