I read it, but SoSac kind of obliterates all your quanta, damages you, and then gives you less turns then dim shield. While effectively costing more.
It's strong, but I think I can make an argument here.
Areas you can improve/amend/correct your argument:
SoSac does drain all your
. However since you would be running Darkness off a mark that is not significant.
Yes it does damage you, please see the part where Asunder + Plague heals you in this combo.
SoSac negates 4 turns of damage (by turning 2 turns into healing). This is greater than the 3 Dim Shield provides.
Yes it does cost more, but it also kills all their creatures.