It's extremely rare for black to get unconditional card advantage like this. Virtually every black "draw a card" effect has some life loss or other sacrifice involved. Look at Phyrexian Rager for example. (The only exception is cantrip spells, which every colour gets.)

...On the other hand, I suppose, the cycle of runners is fairly strong in flavour, and does good things for the set.

I think it'd still be possible to give this "and lose a life", and tie it in with the "undead runners" flavour. Of course, then Makar Runners would look just as out-of-place.