With zero kingdoms leveled I’ve been wrecking all comers at Warlord I difficulty with Boar Rider - Alchemist - Valkyrie - Sunweaver. Game balance: transforms are powerful
The first two are Rares (one step above common, you’ll have them before long if you don’t already), Valk comes from the tutorial, and SW comes from the Wild Plains quest line. Caveat: this team does NOT play itself.
Being in an advanced guild lends masteries which does help a lot, but I’ve raised my difficulty two levels to compensate. 