For zero mana, you can tap and sacrifice the Petal to add one mana of any color to your pool
Countering Let me use an analogy here: Imagine that you are running a race
I don't actually recommend Doubling Season because it's overcosted if you only use half the card More Counters on Themselves: Avenger of Zendikar especially if you add more fetchlands and land ramp, also Taurean Mauler is a worse Managorger Hydra but still amazing with our commander Draw: The Great Henge, Tribute to the World Tree, Esper Sentinel Ramp: Kodama of the West Tree, Defiler of Vigor, Biophagus Protection: Shalai, Voice of Plenty, Deflecting Swat, Bolt Bend, Heroic Intervention, Teferi's Protection, Clever Concealment, Silkguard Combos: Heliod, Sun-Crowned and War Elemental do the same thing as The Red Terror
To summarize, The Master is the doctor's childhood friend, now his nemesis
All three can produce a good number of rats, and the abilities harmonise with each other
