This spell costs {1} less to cast for each instant and sorcery card you own in exile.

Wizards you control get +1/+1 for each instant and sorcery card you own in your graveyard or in exile.

When Arcanis, The Omniscient attacks you may exile an instant or sorcery card from your graveyard, if you do copy that spell. You may cast the copy without paying its mana cost.