The only issue: Karn has been on a Vanguard card before
Stalwart Unity comes out on top because it contains two of the most valuable lands in the entirety of Commander 2016 in Forbidden Orchard and Homeward Path, and while both of these lands are playable in Commander, their high prices are as much a testament to their low supply as to their demand, which could mean they are in line for a significant price decreases
Exile this card and two other cards named Say Its Name from your graveyard: Search your graveyard, hand, and/or library for a card named Altanak, the Thrice-Called and put it onto the battlefield
This process helps keep the game accessible to new players, and keeps the list of cards available from growing so large that the game overall becomes unbalanced
Include low-cost cards in a deck
The fact that its so good against some combo decks, like Storm, that might otherwise be scary matchups, is another selling point