Which Magura brake do you have? I would assume it's a disc. In this case you can often get away with slowly pumping the lever and moving the pistons back into the caliper body. Because the mineral oil used by Magura has a very low viscosity, air can move quite quickly through the system. Pump the lever and keep topping the reservoir up, (avoiding the dreaded sucking sound that signals starting from scratch). After you're satisfied that there is no more air in your system, fill the reservoir full to the brim and put the cap back on, being careful to catch the overspill. Important is to use the correct mineral oil, otherwise you may wreck the seals, or get plants and weeds growing in your brakes. Also, you will probably need a T7 torx to remove the cap if it is a pre Easy Bleed brake. If it is a brake with easy bleed, then all you really need to do is remove the allen key headed stopper in the E.B. bit stick in a syringe without the piston. Fill the syringe with about a centimeter or two of fluid and do what I've said above…