Laveya's demon's curse can cancel an attack along with the events that the attack has caused. In this case, she activated her power when she touched Allen's mana and made it seem as if everything had never happened.
Allen's god's blessing made Allen have to spit out a lot of blood, which he mixed with his mana. To activate it, he had to perforate his own body so that it could activate faster. Because his god's blessing was canceled by Laveya, the hole in his stomach never existed. And all the effects that Allen's god's blessing had, such as: stabbing Laveya and killing all Servus members, never happened.
"Even so, there is still one thing that does not affect this ability of mine,
It is mana.
Even though I canceled your god's blessing, it doesn't mean the mana you spent will return. They only disappeared as payment for using your god's blessing earlier.
