Improvise allows untapped artifacts to help pay the generic portion of a spell's cost. Each artifact tapped this way pays for one generic mana, effectively turning miscellaneous artifacts and tokens into temporary mana sources.
Treasure, Clues, Food, and cheap utility artifacts can all help cast improvise spells without being sacrificed. Inspiring Statuary goes further by giving your nonartifact spells improvise, allowing an artifact-heavy battlefield to power an entirely different class of cards.
