User blog comment:Miskos3/Fairy Tail 541: The Magic of Hope, Review/@comment-7418318-20170626140321/@comment-46.198.235.75-20170627130117

I think it's quite simple.

If Acno's physical body is completly independent from the spirit,then sealing the body in Fairy Sphere wouldn't affect the spirit in the least.Also defeating the spirit wouldn't defeat the body either.

So the second part of reasoning behind Lucy's plan(buying the dragonslayers time and leaving it to them to finish things off),would be invalid.Unless Acno after eating the Ravines of Time of they got assimilated into the dragon body.

The way i understand, it should be something similar to Bege's(One Piece) "Grosser Fater" ability.If You damage the fortress you damage Bege too.Likewise if Luffy and the rest,who found shelter inside bege's Fortress would damage Bege's self inside the Fortress, that Would damage the fortress too