Whenever a creature enters, if it entered from your graveyard or you cast it from your graveyard, return Prized Amalgam from your graveyard to the battlefield tapped at the beginning of the next end step.
2021-03-19
A card cast using its madness ability is cast from exile, not from your graveyard.
2021-03-19
Prized Amalgam's ability triggers only if it's in your graveyard immediately after an appropriate creature enters the battlefield. A Prized Amalgam that's already on the battlefield won't be returned at the beginning of the next end step if it's put into your graveyard later.