Natasha Romanoff, Black Widow

Infinity, deathtouch (Your Infinity Stone Artifacts can help cast this spell. Each Infinity
Stone Artifact you tap while casting this spell pays
for one mana of your choice of this spell's casting
cost.)

When Natasha Romanoff enters the battlefield, search your graveyard and library
for a card named The Soul Stone, reveal it,
put it into your hand, then shuffle
your library.