Why isn’t this just Goblin Ringleader, then? Being a Rally ability, you would essentially be allowed to draw up to 4 cards every time you played an Ally; that’s pretty unfair card advantage. If you have Allies you want to dig for and simply don’t care to draw anything but creatures, this ability is just fine. It all depends on how Ally decks are ultimately constructed, but he’s already too slow for Modern Naya Allies as a four-drop, and Standard needs enough CMC 3 or lower Allies for this to be worth using its ability. Whether Munda sees Standard play or not will be dependent on how much gas Allies end up ultimately having.
As a Commander, this isn’t really too great to build around, as you’d be limited to Red and White Allies and Changelings. As a member of the 99 in a five color Ally deck, though, the ability to filter your draws for Allies could prove useful. He’s a balanced creature in any case, and should help to draw you fuel for the Rally fires in Limited. In Standard, it all depends on what you’d want to end up drawing for Allies - and nothing stands out (as yet) to get excited about.