I'm stuck Anyone have any advice on how to beat it?
Strategies to try for different row compositions:
Summon units:
Bards, Rockers, and then any combination of Ratling / Summoner / Flying Skulls. Give your skulls a funny bone. Summon unit builds are the strongest in this game.
Bulldozer builds:
Using a Pigman, fully-upgraded Excalibur or Sticky, or a Big Boned- buff them up with everything possible. Shields, milk, milkmen, nurses, farmers and blacksmiths. A single juiced up unit can wipe out entire rows and take on the king 1-on-1 if you buff them up enough.
Viking train:
Viking in front! Assassin behind viking! Nurse behind Assassin! Upgrade them all and they will tear through everything. Bonus points for milkman in front or a stoner / kobold behind. Viking benefits from farmer.
And the most important GENERAL tip of them all:
FULLY UPGRADE UNITS!
Early game especially! So easy to get a fully upgraded stoner, skeleton, viking, milkman or flying skull! And these can carry you for the rest of the run! More importantly they will immediately allow you access to another higher-power unit right off the bat that can totally change and inform how you approach the rest of the round.