Deadliest Warrior

Just a quick note for all the Turbo solutions, if you have a Hori Turbo EX2, you can turbo the yellow button slow and the green button fast at the same time. Add a second wired controller and you can just leave this running unattended. Doing it right now, got my 300 Spartans and 100 Beheadings that way, wish I would have seen this first and not used the Knight. Live and learn.

This method will save you 70 minutes of boosting time :)

Using the two controller method after obtaining your 300 hundred Spartan kills you can load up rajput vs ninja
First go to the options set it to 5 rounds you only play 3 but still speeds things up.
Ninja because he has no armor...
Now the trick to completing rounds fast is reloading the level(Just go to warrior select, select the two players then always put the map on Greek Amphitheater) until you get two rounds where you get an instant head-shot with his throwing weapon.
For instance you start the level throw all your throwing projectiles every round if you get a head-shot in two of the rounds then you will get a head-shot every time you rematch in the same rounds...
I guess this game decides the placement of your projectiles from the start of the game pretty crazy

Also if you move forward to the first shrub he might have a higher probability of hitting there head he did for me the second round i had a instant head-shot from spawn then the next round was a instant head-shot from the shrub so good luck on finding your instant kill spot :P

This will speed up your rounds significantly
2 1 second rounds + a 4 second round really is a lot faster than three 4 second rounds

considering you already have 300 kills with rajput killing Spartans I did the math

My round completion time=6 seconds
other method=12 seconds

6*700=4200 seconds=70 minutes

12*700=8400 seconds=140 minutes

Also to get a 4 second round run straight up to the ninja and press X,Y,X,Y

If anyone has anything to add to this solution let me know in the comments :)