It doesn't 'reflect' magic at all. It reflects anything that it counts as a projectile, which includes magic missile, but doing so also dispels the buff, so you can target it with impunity after that, and it has no defence at all against saving throw spells.
This is just a case of playing smarter not harder.
I don't know, may be it got nerfed
It definitely reflected more than one thing on me, including a couple of arrows and yes, the magic missile. It was on a fairly old patch though, so may part of the challenge can be attributed to me not knowing the mechanics well enough yet.
