The reason why mf was able to triumph
:
"i'm too up to fight
. To fight a monster i have to become a monster!"
:
"i'm too up to fight
. To fight a monster i have to become a monster!"
"Don't become monster to defeat one " -- 
These "Miss Fortune is trash" posts are starting to get really old (if that's what this is.)
Reading her lore, it's definitely in character to crush Gangplank in such a way.