Arrow S5 |OT| You thought you were out, but Manu Bennett pulls you back in.

Okay so we've got:
Thea's back
Felicity on the island? Diggle too?
Yao Fei hallucination?
Origin of the Deathstroke mask on the Island
Black Siren and Chesthair meet, she kidnaps him
Dolph on the island
T Spheres getting even better
Stardust's Sampson is back
Merlyn appears in the hideout out of nowhere AGAIN
Diggle vs Ninjas
Prometheus vs Everyone
Talia vs Nyssa
Siren vs Dinah
Anatoli returns Oliver to the island and they hug it out aww
Evelyn with a gun, her and Thea and some other girl on the Island?
Olicity (I believe this is a flashback to S4)
Wild Daddy
Janey's got a gun, I mean Felicity. Janey is on Supergirl.
Nothing else of note
.
.
.
.
Oh, Deathstroke's back.
I think the other girl behind Thea might be Zoe Ramirez. With Siren kidnapping Lance, it seems like Chase might be kidnapping people close to Team Arrow to draw them to the island and make his point about people close to Oliver suffering.
 
We get a short view of Roy sitting at home, being happy, then it cuts to Thea and someone fighting, back to Roy smiling thinking how nice it is to have a calm day.
 
Oh wow, the synopsis for #5.21 sounds good and explains how a few characters come back.

#5.21 "Honor Thy Fathers"

CHASE CONTINUES TO TORMENT OLIVER — Oliver (Stephen Amell) returns to the mayor’s office and faces one of his most pressing issues yet – the forced release of dozens of violent criminals prosecuted by Adrian Chase (Josh Segarra). Meanwhile, a crate is delivered to Oliver’s office containing a mysterious corpse encased in concrete. Laura Belsey directed the episode written by Marc Guggenheim & Sarah Tarkoff (#521).
Of course if Chase is a criminal, his prosecutions are suspect! That's an actual thing! Also... Robert's body?

Roy to flip into the scene confirmed!
There's been a few rumors floating around, but none of them seem substantiated. I wouldn't get your hopes up.

But hey, this one came from a pretty reliable Vancouver film set scout, so someone light the
Wozzly
signal:
SUSANNA THOMPSON. QUEEN FINALE.
Oh and Prometheus
kidnaps Samantha and William and takes them to the Island
. BECAUSE OF COURSE HE FUCKING DOES!
 
So why is Oliver going back to Slade? To help him finish Chase?
When Prometheus says in the trailer "you can't beat me, we had the same teacher," maybe it makes Oliver realise that he needs to go back to his older teacher Slade for further training to catch Adrian off guard with new techniques. Not sure how that would go down though.
 
So why is Oliver going back to Slade? To help him finish Chase?
The finale is
set on the island. Seems like Chase has been abducting people close to Oliver and keeping them there. When you're up against a foe, on an isolated island, who's prepared for any reasonable thing you might do... who else can you can call but one of the strongest fighters in the world who's already secretly there and waiting?
 
I hope we're getting a
more calm and business-like Deathstroke compared to the "muh Shado" version we had previously. Hopefully all that island time and jobbing to Thea chilled Slade out a little.
 
When Prometheus says in the trailer "you can't beat me, we had the same teacher," maybe it makes Oliver realise that he needs to go back to his older teacher Slade for further training to catch Adrian off guard with new techniques. Not sure how that would go down though.
Hmm. Oliver has been trained by many people though, including Slade.
 
I think they're going to keep to the idea that while Oliver is a superior combatant, Prometheus is better prepared and has a contingency plan for any fighter. His training is specifically to counter Oliver too. Prometheus is ten steps ahead you might say.