The Splear Mirror is very powerful. As a high-grade artifact in the domain of space, its might is enough to toy with the majority of True Gods.
But its might is not that strong; at least when faced with great divine power, anything that has not also touched that realm is merely icing on the cake and cannot play a decisive role.
It can even be said that even if another great divine power wields a high-grade artifact.
Unless there is a significant gap in strength between the two, it is also difficult to easily restrict each other's actions in their home turf.
Even Hypnos, originally in mythology capable of putting anyone to sleep, needed Hera's allure and Aphrodite's girdle's support to barely ambush an unsuspecting Zeus.
Thus, Laine never planned to act personally, nor intended for an avatar with less strength than the Divine King to take action.