Thalia, Guardian Of Thraben , Glowrider , and Thorn Of Amethyst all make all noncreature spells one more mana to cast - and these effect stack if more than one is on the battlefield
As a card, The Chain Veil lets you double up in your planeswalker activations, at the slight cost of losing a little life if you dont use a planeswalker loyalty power
Outside of Commander, Walk-In Closet // Forgotten Cellar could see competitive play too, replacing Crucible of Worlds in existing lists
My first ever piece of Magic content was on it and, although I didnt draft power, I would definitely not be writing this right now if it werent for Vintage Cube
Whenever a creature under your control would deal damage to a player, it also deals that much damage to the chosen player