Hi there. First of all, thank you for all the time you spend answering our questions! We had an interesting interaction during a commander game. I control Yomiji, Who Bars the Way. My opponent controls Athreos, Shroud-Veiled and puts a coin counter on my Raff Capashen, Ship's Mage. When Raff dies, does it go back to my hand or to the battlefield under my opponents control. Would it make a difference if Raff were my commander?
It depends on whose turn it is.
Whoever is the active player will put their trigger on the stack first, then the other player’s trigger will go on the stack above that trigger and resolve first. (If neither player is the active player, then it goes in turn order starting from the active player.) Whoever has their trigger resolve first will move the card out of the graveyard to the appropriate zone and then the other player’s trigger won’t do anything.
If Raff is your commander and you send him directly to your command zone, then neither effect will trigger here.