Spell Copy decks create copies of instants and sorceries already on the stack, getting additional effects without casting an entirely new card. Copies usually inherit the original spell's choices while allowing new targets where an effect permits.
Mizzix's Mastery can copy an entire graveyard of spells through overload, while Kalamax, the Stormsire copies the first instant you cast under the right conditions. Magecraft rewards the copies even though most copied spells aren't themselves cast.
