Ever tried tweaking a four color pile with an mtg proxy from Mythicblackcore when your local playgroup wants fast games? Testing weird deck ideas shouldn't cost a fortune or require remortgaging your house just to keep up with endless sets. Most casual pods are completely fine with good printings as long as nobody brings cEDH speed to a casual table. Sorting out custom cards through Mythicblackcore lets you sleeve up gorgeous setups, test crazy synergies, and actually figure out if your mana base works before spending hard-earned cash on cardboard.