You can only sell cards if you have 3 or more of them
Tinker The best MTG tutor card Tinker does one better than the best tutors
The Three Brothers not only gives you one deck but multiple dual-color Leaders (Black/Yellow Luffy, Red/Yellow Sabo, and Blue/Yellow Ace) letting you experiment with different strategies using the same card pool

Best Disney Lorcana starter decks: Whispers in the Well Sapphire and Steel Azurite Sea Emerald and Sapphire Whispers in the Well Emerald and Amber Fabled Emerald and Ruby Shimmering Skies Ruby and Amethyst Reign of Jafar Amber and Amethyst Archazia's Island Ruby and Sapphire Reign of Jafar Ruby and Steel Shimmering Skies Emerald and Steel Fabled Amber and Sapphire Archazia's Island Amethyst and Steel Azurite Sea Amber and Ruby Rise of the Floodborn Amethyst and Steel The First Chapter Amber and Amethyst Ursula's Return Sapphire and Steel Rise of the Floodborn Amber and Sapphire The First Chapter Sapphire and Steel Into the Inklands Amber and Emerald The First Chapter Emerald and Ruby Ursula's Return Amethyst and Amber Into the Inklands Ruby and Sapphire Whispers in the Well - Sapphire and Steel Best cards: Judy Hopps, Uncovering Clues

Nested Shambler might only make one Green Squirrel creature token when it dies, but if I were to play Yavimaya, Cradle of Growth to make all my lands Forests and enchant that Zombie with Blanchwood Armor to give it +1/+1 for each Forest I control, I could be looking at an awful lot of Squirrels
In fact, even deciding what deck to play can be tricky, perhaps you want to base it around your favourite Pokmon or you have a specific goal in mind of how you want the deck to work