Thing is, with the Musical confirmed to feature more screwy time traveling, we need just one more and only with the characters from Supergirl and Flash similar to ep 22 of the scarlet speedster and Arrow ep 69 where heroes from other shows in the Arrowverse come to help one another with an emergency situation but for this one, they should have Supergirl, Superman and a yet to be redeemed Silver Banshee Siobhan Smythe link up with Team Flash on Earth One against Savitar and his forces. Which means that instead of making the seasons on all 4 shows end on the same week it's best for the producers to have each season of each show end with 2 at a time per week just this once. Besides, Barry's actions have brought an impact on everyone else since Cisco urged him to tell anyone that Zoom traumatized him into immaturingly screwing with the Timeline which upsets Sara and Jaxson and crazed out Team Arrow. But rather than being big on having everyone in the Arrowverse, it should just be the characters from Supergirl and Flash that take on Savitar and his cult and maybe the Black Flash himself. Now to make things more interesting as shown in these fan made posters below regarding the War against the Meta God on how Kreisberg and his staff and crew are to pit the characters against who.
War Against Savitar
Kid Flash, Jesse Quick, Silver Banshee Prime, Vibe, Caitlin, and the Red Baron Flash of Earth 19 to take on most of Savitar's Superspeedster Ninjas and any metahuman allies to the speed god
Savitar Rising
Supergirl and Barry to face off against The Black Flash who as Zoom from season 2 was the one responsible for distraughting Barry into messing up the timeline through creating Flashpoint. Of course all Barry and Kara need to do is keep fighting the villain until Savitar and his cult are defeated and then let the Black Flash escape to reemerge as the main antagonist for season 4 to antagonize his equal once more.
and
Savitar's Day of Reckoning
Jay Garrick and Superman, the first generation of modern day heroes in the Arrowverse are to defeat Savitar over in Rajhastan at the temple on the hill dedicated to him and Savitri along with some of his escorts. Whether the Speed God is the actual Hindu God of Motion in the Arrowverse from Earth 1, Earth 38, the same version from the comics, Jay Garrick is the one that should defeat the villain the same way Optimus defeated Megatron in the 2007 movie game but with the philosopher stone alive and then let the Black Flash kill him for his power after he is locked up or pathetically Barry or Cisco's future self for such childish excuse then Jay should just kill him with the stone by shoving it into Savitar's chest.
This is how CW can do better on the shows before this upcoming fall folks, which is why some of you need to persuade Kreisberg, Berlanti and Adler into holding off from filming the 5 remaining episodes of Flash and Supergirl until April because that way, some of the stars from other shows regarding Tyler Hoechlin and Italia Ricci can get back to Vancover and reprise their roles from last year after they finish wrapping their parts in shows Teen Wolf and Designated Survivor. Because most of us really don't want them to miss out on returning for more Supergirl in the second half of season 2 and since The Flash (Barry) was responsible for causing such problems for everyone in the Arrowverse, it would be best for CW to end Arrow season 5 and Legends season 2 a week or 3 ahead of Supergirl season 2 and Flash season 3 rather than like they did last year so that the current wave of seasons ends with the season finale of the show that started it last Fall. One good reason this idea of a season finale crossover should be worth it is because of how epic the Flashs' skirmish with Savitar and his disciples turned out in the 90's and it would be super cool if they made it happen in the finale but only with Jay, Wally and Jesse as the combatants from the comics participating in the war against the ultimate Villain Savitar!