Spending resources to slow down one opponent also slows you down relative to everyone else at the table, but spending them to accelerate towards your wincon assuming its an instant-win combo puts you ahead relative to all of those players
When players think of finishers in Commander, one of the first cards that comes to mind is almost certainly Craterhoof Behemoth
(They're artifacts with " , Sacrifice this token: Add one mana of any color.") Instant Color tag templates(None) Arcane Denial Counter target spell
cards to 1 of your Characters." as described in the effect
These are good value reprints too, including Dryad of the Ilysian Grove, Apex Devastator, Uro, Titan of Nature's Wrath, and Mana Reflection, plus two great lands in Vesuva and Yavimaya, Cradle of Growth
Manaplasm Its like prowess but for an ooze