Undaunted is a static ability that functions while the spell with undaunted is on the stack. Undaunted means “This spell costs {1} less to cast for each opponent you have.”
May 3, 2019 · War of the Spark
Improvise is a static ability that functions while the spell with improvise is on the stack. “Improvise” means “For each generic mana in this spell’s total cost, you may tap an untapped artifact you control rather than pay that mana.”
January 25, 2019 · Ravnica Allegiance
Improvise is a static ability that functions while the spell with improvise is on the stack. "Improvise" means "For each generic mana in this spell's total cost, you may tap an untapped artifact you control rather than pay that mana."
January 20, 2017 · Aether Revolt
Improvise is a static ability that functions while the spell with improvise is on the stack. “Improvise” means “For each generic mana in this spell’s total cost, you may tap an untapped artifact you control rather than pay that mana.”