Galazeth Prismari dies, triggering Nim Deathmantle, causing you to pay ({4} magic symbol) to return Galazeth Prismari from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Galazeth Prismari enters the battlefield, creating two Treasure tokens.
Activate two Treasure tokens by tapping and sacrificing those, adding two mana of any color.