The souvenir is made of Adamantium, which Stryker wants more of for his experiements.
As explained here:
During one of their missions, while under Stryker's command, Team X is sent to search for and retrieve a mysterious meteorite - later discovered as Adamantium - from a diamond trafficking operation in Lagos, Nigeria. They attack a compound there and ...
You are missing out few, will try to answer in chronology:
From Supergirl S05E08:
Tim Burton's Batman Movies: Alexander Knox (Robert Wuhl) cameo who was the first to report upon The Joker's crimes
Titans: Hawk (Alan Ritchson) and Jason Todd (Curran Walters) cameo
Batman (1966 TV series): Robin (Burt Ward) shouts "Holy Crimson Skies Of Death!"
The real world reason for a "NO" answer is - You don't want to have your show blocked in any place because you used a symbol someone recognize as evil. Monster drink "praising devil" case.
BUT, I've found in one episode (8th) that the "60 sigils" are very close to 72 sigils of demons in Ars Goetia. So I looked and compared a sigil from the show.
It looks ...
To be honest, he was hitting the keys (or rather that one particular key) to indicate his lieutenant (Lakeith Stanfield) to ask a specific question. He just seems to enjoy the theatrics of it.
Though initially, I thought he was hitting the key whenever the investigation got derailed from the main objective. It was an annoyingly, polite way to tell the ...
It seemed to be he hit the piano each time he suspected the one being questioned was lying. If I remember correctly it occurred after the flashbacks to what actually happened and to what the person says.
It also got a reaction from the person being questioned, making them nervous.
It sounds like a few tropes are in effect here, though I can't find a single term that encompasses all of them.
He is lucky that he's wearing Plot Armor that protects him from the other bad guys.
The element of luck is Lampshaded because it's always noticeable.
And yet his luck runs out in the end, which could be an example of Chekhov's Gag:
The fact ...