Summersong 
"[@AC97":](/pony/season-9-discussion-thread-no-spoilers/post/4566452#post_4566452
)
Grogar_*did_* come out of left field other than a handwave mention in a children's storybook (which could easily have just *also mentioned Tambelon* if you so desperately needed it telegraphed.
)
The Pony of Shadows came out of left field after a brief mention as a boogeypone.
Chrysalis came out of left field with no prior mention at all.
It's called a_*plot twist_*. That's how they work.
Using the entire history of the show as the impetus to summon the Ultimate Evil would be the best possible way to end it, but they didn't do that. They did another typical two-parter where **FRIENDSHIP'S POWER IS MAXIMUM-ER**, the only difference being that Twilight is becoming the princess.
aka Summersong
Grogar
The Pony of Shadows came out of left field after a brief mention as a boogeypone.
Chrysalis came out of left field with no prior mention at all.
It's called a
Using the entire history of the show as the impetus to summon the Ultimate Evil would be the best possible way to end it, but they didn't do that. They did another typical two-parter where **FRIENDSHIP'S POWER IS MAXIMUM-ER**, the only difference being that Twilight is becoming the princess.