This is my opinion. When SoV brings to the game, there are some issues:
1. It will make the stall deck more than before.. This stall deck is creature-less and permanent oriented. In summary, it will lead to a boring game and not a creative deck to be.
2. There should not permanent that attack directly to player except weapon, right? So, Shard of Void means as "second weapon" which is cheating.
I think that the game should be more creature oriented rather than permanent oriented, because permanent oriented deck is owned only by pulvy, butterfly, deflag, and steal. So, I think SoV should orientated more to creature.
My Suggestion is:
SoV: half the atk power of targeted creature. The ability is now "corrupt". Then, atk +2 if darkness creature.
Corrupt: decrease opp max hp by its atk power.
With this, SoV is more "creature oriented". It is more creative because the power depends on targeted creature. SoV also can be used to "lobotomize" opp creature. SoV also needs creature to attack, so no permanent that acts like weapon anymore. It is more fun than before..