The Season of Heritage in Pokemon GO will host one of its first mini-events of the season, the "Dragonspiral Descent" event that introduces a new Pokemon from the Unova region. Druddigon, the Dragon-type Pokemon will make its debut in Pokemon GO as well as its shiny variant.
As part of the ongoing story in Pokemon GO, Professor Willow discovered a mysterious historic gate on one of his expeditions. That gate has now been activated thanks to the efforts of trainers during Swinub Insense Day. The Dragonspiral Decent is a callback to the Dragonspiral Tower from the Pokemon Black/White games where either Reshiram or Zekrom can be found.
These two Pokemon and their shiny variations are also in Five-Star Raids in Pokemon GO during the event. The opening of the historic gate has caused a surge of Fire-, Electric-, and Ice-type encounters in-game. Druddigon can be obtained at the end of its associated Field Research Tasks. Druddigon will also appear in 3-star raids.
The Dragonspiral Decent event will begin December 7th at 10 AM local time and run until December 11th 8 PM local time. Additional Pokemon appearing in increased amounts during the event include Seel, Vulpix, Sneasel, Dratini, Mareep, Bltizle, Trapinch, Deino and Fire-type Darumaka. The shiny variants for those Pokemon will also appear. Dragonair and Vibrava will also appear in increased numbers. An event themed Collection Challenge will take place and players that catch all the required Pokemon will be rewarded with 1000 XP and 3000 Stardust. The Mega Evolution of Steelix will also be available during this event.
Draddigon is, as the name suggests, a Dragon-type Pokemon. Its introduction to the Pokemon GO Unova Pokedex follows a strategy that Niantic has been doing this year. Rather than release them all at once as they did for the first 2 regions, there are now specific events themed around the release. Dedenne was recently released in the Season of Mischief and this strategy makes it an event and draw-out playtime. Pokemon GO's Unova dex still has some places left to fill but it has filled out over time.
This is a long list of Pokemon with increased spawns for this event, but as of writing, there are no sources indicating that there are increased odds of finding shinies. Players will either have to hope that there are increased odds to go along with the increased spawn rates or revert to using incense to lure out larger numbers of Pokemon. The Field Research tasks that will reward Draddigon are also unknown at the moment.
Pokemon GO is out now on Android and iOS.