HOW TO INVADE FAIRY TAIL?
Throw a strawberry cake inside the guild from the window while Erza's in it.
Lock Gray and Juvia in the same room.
Put a sale banner on the fish store.
Tell Mira that Laxus likes her.
Tell Elfman the Lisanna is dating Bacchus.
Tell Wendy that Carla is going back to Edolas.
Tell Carla that Wendy ran away with Jellal.
Tell Erza, that Jellal ran off with Meredy and fake a marriage card.
Tell Gildarts that his wife is sleeping with someone else.
Tell Lucy that Loki and Aquarius are getting married.
Tell Levy that Mavis just chose her as the tactician's successor.
Tell Brickslow, Freed and Evergreen that Laxus is on a date.
Fake a letter from council to Makarov explaining that Fairy Tail has fallen into a debt.
After doing all this, it is guaranteed that you can invade Fairy Tail successfully.