Let it Die - Jackal Y vs Pale Wind - Nightmare speed farming 

G8 makes light work of most things, including Pale Wind on nightmare. This is how I farm 44ce Milk really fast but it requires a pretty end-game setup. Most of the decals can be swapped around but Flash Boiler is the key.
There is one elevator and one escalator on the way to nightmare Pale Wind, ensuring I automatically arrive with plenty of rage to start punching. After the kill, simply suicide for a free revive and repeat. There is very little down time and no extra shrooms required, just loop until you run out of entry money :)