Enameled Dragonplate everything, either the Sword of the Temple Guard or the Sword of the Forgotten (I only have a warrior so this is the most I can recommend), Boss Star III to summon soldiers, Boots of Leaping, the Speed Ring, at least Programmaticon IV, Twilight Glasses, and a good browser like Microsoft Edge. (Chrome keeps crashing even with an empty cache.)
Kill all enemies on the map, summoning soldiers as you go, before collecting the mushrooms and fighting the bosses. Use flags to move if you want.
Try using a certain unit or mix of units. I find that cheap soldiers work just fine. Either command them to defend you or attack the nearest enemy they can find (
That's the most I can help you with