There's no extra bonus if you control more than one commander
Leyline of PunishmentLeyline of Punishment (5,937 Inclusions, 0% of 2,229,769 Decks) As the long-time pilot of a Sapling of ColfenorSapling of Colfenor deck, I can tell you that there are entire decks that just shut down when the phrase "players can't gain life" enters the chat, but most folks playing Leyline of PunishmentLeyline of Punishment aren't trying to shut you down so much as just keep things on an even playing field for their Group Slug shenanigans
But Magic: The Gathering FINAL FANTASY joins 14 other sets in Standard, so decks that have been optimized over the past three years have little room for new inclusions
However, I've probably missed a few I'm not perfect
The main downside comes from the floor: Loot does nothing without a bunch of other permanents in play and gets a nice, fat target painted on its head whenever you cast it
Its never going to be