This story is a sequel to The Inner Conflict
Peace and serenity has finally returned to Equestria and Earth ever since the destruction of Soundwave and his machinations. But little did they know that it was far from over. Megatron and his Decepticons are now back to finally launch their ultimate attack on Equestria before they precede to assault other familiar worlds. For Megatron, it will be his greatest triumph, but for the ponies... it will be their greatest doom. It is up to the Magic of Friendship to light their darkest hour.
Note: This takes place after MLP: FIM season 8 episode 11—Molt Down.