The damage is dealt by the same source as the original source of damage. The doubled damage isn't dealt by Obosh unless it was the original source of damage.
Obosh, the Preypiercer
Paying {3} to put your companion into your hand is a special action. It doesn't use the stack and players can't respond to it. Once you take this action, you may cast that card if it's legal to do so before any other player can take actions.
Wizards of the Coast has issued functional errata for the Companion mechanic. Instead of casting companions from outside the game: Once per game, any time you could cast a sorcery (during your main phase when the stack is empty), you can pay {3} to put your companion from your sideboard into your hand. This is a special action, not an activated ability. It happens immediately and can’t be responded to. It can’t be countered or stopped by cards like Phyrexian Revoker. For more information please see https://magic.wizards.com/en/articles/archive/news/june-1-2020-banned-and-restricted-announcement
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Daarken
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
