I was told to use magnus and probably 4 blade, 2 blade don't cut as good therefore less bloodtrail, get a good cut on contact broadhead, I am hunting backs with a recurve this spring.

I use a 3 blade Montec 125 grain cut on contact. With my bow they fly like field points. I've taken game up to a 1600 lb Buffalo (30 yards complete pass through 60 lb draw weight). I see no real benefit of expandables when the fixed is flying as well and gets better penetration. I will be using the same broadhead on a water buffalo later this year.

fixed blade for sure - magnus will do the trick

Fixed blade....period.
Why take a chance? Your shot is only going to be around 15 yards...give or take a little. With some time at the archery range, you and your equipment should be tuned to shoot a fixed blade where you want it every time,,,well almost every time.