Bug with Rakdos Joins Up and Abuelo's Awakening
Playing on PC. I was playing against a deck that had Rakdos Joins Up in their graveyard. They played Abduelo's Awakening on it and returned it to play as a 1/1 creature. The issue is that they later played a Hulking Metamorph and copied the Rakdos Joins up creature. This then caused the legendary rule to apply and the metamorph was sent to the graveyard. They proceeded to infinitely loop this process. The issue is that the legend rule is a state based action and no creature dies, so this should not cause the dying trigger on Rakdos Joins Up! Please correct this as this not how the rules work.

-
Rezzahan#77802 commented
Metamorph is a creature at all times, as it makes that exception to its copying process. It enters, and leaves, the battlefield as a creature. And since state based actions are checked before triggers are put on the stack, the Metamorph is back in the graveyard to be targeted for reanimation by its former version's trigger that just went off. And as it copied a legendary permanent, it is a legendary creature, that dies, thus triggering both its own and the original Rakdos Joins Up dies triggers.
This is a legitimate combo.