What it does
Improvise lets you tap your artifacts to help pay a spell's generic mana cost. Each artifact you tap this way pays for
. So if a spell costs 
and you tap four artifacts, you only need to pay 
from other sources.
The key nuance: Improvise only works on generic mana (the colorless numbers), never colored or specific colorless symbols like
or
. Also, you're tapping the artifacts—not sacrificing them—and crucially, the mana value of those artifacts doesn't matter; even a Sol Ring or a zero-cost token each only contributes
. Tapped artifacts and artifacts with summoning sickness can both be used, since tapping for Improvise isn't an ability that requires the haste-style timing of creatures attacking.
In Commander, Improvise shines in artifact-heavy decks, especially Treasure or token strategies, letting you cast expensive spells far ahead of curve while keeping your actual mana untapped for interaction.













