I beat the first major boss: Dancing Lion from trailers. I’m not good at these games. Took me a dozen+ tries. I used the NPC summon because they tend to have story elements.
NPC doesn’t do much damage and dies quickly in phase 2. It helps but not that much.
So far it’s not that hard. Biggest hurdle is even with +24 weapons I cannot do sufficient damage to the wickermen or new dragons. I assume it’s the leveling items?