School Raze (Season 8 finale) 

Alright, how do I sum up this finale with one line?

Uhum uhum...

BREAKING NEWS! FILLY GETS ARRESTED FOR DRAINING ALL THE MAGIC IN EQUESTRIA AND TAKING OVER THE SCHOOL OF FRIENDSHIP. MORE NEWS AT 11!

You know, there are times when adults cannot even get that evil nor reach those cold plans to the point where you are a psychopath with no remorse at any moment.

Episodes needed before this finale: School Daze, What Lies Beneath, Marks for Affection and Friendship University.

The definition of Cozy Glow becomes somewhat confusing about what her backstory is. A little detail that lot of fans skip is that we all knew the backstory from the mane 6 and the CMC(we knew them from the start obviously but I want to remark it), the students with A Heart´s Warming Club, Surf and Or Turf (for Silver Stream), the two Spike episodes (for Smolder), What Lies Beneath (for Ocellus); and Dolores teen years with the Parents Map, so they had nothing left to hide and their intentions were pretty clear. No mysteries left around them. 

The only two CHARACTERS that didn´t show all the reasons behind them were Neighsay and Cozy Glow. You only knew that Neighsay was competing against Twilight for proving his vision right and that Cozy Glow....the only two signs you would notice are the little gestures, how she is attracted to the Tree of Harmony and that her answer for the 6th element for her was power, not magic. 

I swear, you cannot leave behind background or subtle things at any moment because they will caught you out of guard for a few aspects. Sure, they deliver a pretty predictable plot but that predictability doesn´t mean that it doesn´t hold surprises for your own expectations.

If you paid attention to Friendship University, it subtly hints that Cozy Glow had worked for Neighsay as a spy but it turns out that Neighsay didn´t even know her in the first place and even looked at her down when she was in charge of the school when Equestria was in great danger with the lack of magic around the continent. 

The EEA "racist" vision would have worked in season 1 (this explains why the mane 6 acted so harshly with Zecora) and the bubble that preventS for anypony to leave the places they know and dwell. Basically, an education for them exclusively because the other species have caused trouble in the past, so in theory, they wouldn´t get those lessons. However, that doesn´t mean the EEA doesn´t teach the values of friendship, just that it´s for ponies.

This last line becomes relevant when Cozy Glow captures him by using Neighsay´s view against his own creator. 

The partner for this plan is Tirek and he accepted that deal just for capturing the mane 6 in the Tartarus and leaving Cozy Glow with all the power. However, Tirek is also stupid for not thinking that he cannot escape from the Tartarus so he has to endure Pinkie´s jokes all the time. GG, well played buddy. 

So this leaves us to the actual character that matters: Cozy Glow. 
There were hints that she was planning something evil inside her mind.....but not THAT level of evil and that´s where the predictability becomes a joke and you analyze how manipulative she is.