mtg treasure commander deck Ragavan, Nimble Pilferer PIRATES and Magic Custom each player mills a card Custom Treasure Chest Deck Box

This ensures you can not only keep casting spells, but potentially casting multiple spells per turn

On the other hand, people who strongly support the substitute technique tend to focus on the instances in which this works well (dual lands) and gloss over the fact that some of the Reserved List cards most important to the Commander format (Wheel of Fortune and Gaea's Cradle) don't have substitutes that are anywhere close to their original

Sultai decks also have access to lots of the best infect cards to help this shapeshifter clone the best targets

Dualcaster Mage is awesome no matter what spell it copies

Planar Genesis