Bloodgruel and Targeting

So, I was thinking the other day that our SM can theoretically get 4 wounds back per turn and this question popped up:  Can a slaughtermaster cast a spell at nothing/terrain feature simply to trigger bloodgruel?

My two points for thinking yes:

1.  The BRB and our spells do not designate what a "target" is, only what rules we have to follow for targeting.

2.  The Rune Maw can create a situation in which a spell has no target but is successfully cast.

Technically you can simply cast the augments at himself and The Maw can be cast at at point of the table (within range).

Good point...what about hexes and bonecrusher?

Both Magic Missiles and Hexes need an actual enemy unit to target them at.

The Maw is categorized as Direct Damage and per the BRB FAQ must be placed so it "targets" an enemy unit.

Ahhhhh, you're right.  It's right there in the book.  I didn't read far enough.  Can only every be cast on enemy units.  Soooo, I can't even antagonize neutral units