OE+FW is 2 cards + 6
+ mono snipe + 5 damage per turn, or 1 card + 8
+ mono snipe + 5 damage per turn.
Grave Lurker is 1 card + 5
+ duo snipe + 3 damage per turn.
There is a discrepancy of 3
. 1 of these comes from the duo cost, and the other 2
probably come from the less damage. The ability to be untargettable by other creatures only is worth around 1/2
if I had to say, so 5
is fine.