Tonight at midnight Pacific time the Marvel Tsum Tsum Game will go down for maintenance for a few hours. When it comes back up Doctor Strange and Ancient One will be added to the Orb box!
For a limited time the chance of getting them from the orb box will be increased AND they will start with 5 luck! These bonuses will last until the end of day Oct 29th.
Also, similar to the new Spider-Verse characters this month, the Doctor Strange characters will have an extra 500 HP/ATK/DEF through the month of November.
In addition to the new Tsums, the official page also announced
the Doctor Strange Event will start Wednesday! We don't know much about the event yet; however, it sounds like you will be able to get similar prizes as the Spider-Verse event (ISO, Orbs, etc). We will be sure to let you know once we have more details!
As for the new characters they both have a new ability "Boost Damage for Shield". Based on the description it sounds like some new Villains (or Villains in the Doctor Strange Event) will have the ability to create a shield which you have to damage (via clear Tsums, skills, bombs, etc) to destroy. This ability will increase the damage done to shields.
Here are the official preview videos for the two new Tsums!