@ohgodwhy: Deliora wasn't that huge.
As for the 100 monster challenge. Take in mind what we got out of that was that. Erza's offensive power and stamina and speed has shown good improvement. Although if I recall she came into the room with her strongest offensive sword.
Although I think V2 Killerbee can tank it and if he can Erza's offensive style which involves swordsmanship is going to fail against KB due to his own speed, but of course strength and durability forms.
Laxus is a more credible threat but against unless he successfully distracts for example Hachibi form so Erza could land some credible damage, (Hachibi seems to be vulnerable to cutting force) I don't see how they can win.
Again Menacing Ball and of course his giant sized whirlwind which really destroyed a huge chunk of the forest and HAchibi himself was just a small form in the middle in that scan drawn by Kishimoto.