A double strike creature that gets bigger from playing five-mana value spells doesnt really have a place at the table right now
A 4/4 Golem for five mana that gets -4/+4 whenever it blocks or becomes blocked, the key appeal of Karn is the manner in which it interacts with your other artifact cards
Sometimes your opponent will have removal, but many times they wont and it even gets the Bird out of range of many red removal spells anyway
A lot of players do this relatively early on so that they can afford all the items necessary to furnish a top-notch store further down the line
Whether you look for a flare as a free spell, a fetch land, or a feline (namely Ocelot Pride), you could land on a great boost for your Modern deck
In order to create visually shiny and opaque textures within the illustration and frame design of a card, certain elements are under-printed with different values of white ink