The preps I took were super useful for today's bosses, guess I was just lucky. Currently top for XP and Piety with 429 XP and 497 Piety but seeing that I was only 11 XP more than the 2nd position, I definitely think that max possible XP can be pushed higher. Started with Binlor (Knockback, Might, 2 Stone Heart to max Magic Resists), then Dracul (for 15% Phys. Resists and Sanguine to fight Boss 3, also took Blood Curse for higher fireball damage for the Phys. Resistant Rock Boss) and finally GG (Humility, lots of Cleansing for the mop up and beads, Enlightenment).
Today's preps (the Bear Mace at least, and Black Market) and the shop pool items look very suited for a Rat Monarch run too,

[Oh, and if there's anything "bad" about today, it's that all 3 mana boosters are located in 1 quadrant of the map away from you. So, you will be stuck at 10 mana for a long time unless you explored there first]