When Inga dies, it's second ability and Nim Deathmantle trigger.
Resolve the Inga trigger, causing you to draw three cards.
Activate Mind over Matter by discarding a card, untapping a mana-producing permanent.
Activate the mana-producing permanent by tapping it, adding at least ({1} magic symbol) .
Repeat steps 4 and 5 two additional times.
Resolve the Nim Deathmantle trigger from step 2, causing you to pay ({4} magic symbol) to return Inga from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Inga enters the battlefield, its first ability triggers, causing you to scry 3.