When you play a traditional best-of-three match, youll go to your sideboard screen in between games
Likewise, foils are going to start very, very high, and retrace only 30-40% as peak supply rolls through
If you do, untap all attacking creatures and after this phase, there is an additional combat phase
Let's lump them all together out of respect and get to the real chonkers: Polar Kraken Denizen of the Deep Spawnsire of Ulamog Darksteel Colossus Inkwell Leviathan Titanoth Rex It That Betrays Blightsteel Colossus #26
Shadow, Mysterious Assassin* The Final Fantasy 6 Commander Deck version of Shadow is a decent enough creature, but deathtouch isnt a great evasive ability and to make the best use of his ability he really needs to get in so you can sacrifice whatever permanent you sneaked in for cards and damage
Some folks sell custom sets or run Kickstarter campaigns for entirely new expansions