Go to the Arena Store, at the top right is a text box that says Redeem Code. Enter a valid code, make sure you type it accurately since codes are case sensitive , and press enter
Best as a Commander I chose Firion, Wild Rose WarriorFirion, Wild Rose Warrior for Best As A Commander over Cid or The Emperor of PalameciaThe Emperor of Palamecia
Bladeback Sliver It is very easy to find yourself hellbent after unloading all your slivers onto the battlefield
Manamorphose Manamorphose does exactly what it says on the tin, giving you back the same mana you pay into it in whatever color combo you want
Vanguard was a supplemental product made not to be sold but given away as part of an in-store league (something called Arena, sort of a precursor to Friday Night Magic )
Since Persistent Petitioners is a Human, and you can use them to mill yourself, the strategy is simply to throw a bunch of Persistent Petitioners into the deck alongside a bunch of copies of Slime Against Humanity, mill yourself out, and then play more Persistent Petitioners to cast those copies of Slime Against Humanity from the graveyard
