Hi dude!
You already have 8 permanent options to mill your opponent down.
The
Millstone needs to be actived with mana to do what your other options do for nothing else than play them.
Instead you should use these mana to grant you are
alive to play your things or answers to your oppoments' threats. And
Root Snare and
Sleep do it very well in this deck.
This is just a way to control the match until your next turn to activate your milling effects.