Hey fellow Planeswalkers! When building a deck in Magic: The Gathering Arena, always start with a clear strategy in mind. Focus on a key theme or combo that your deck will revolve around. Make sure to include a good mix of cards for early game, mid-game, and late-game situations to ensure your deck is well-rounded. Don’t forget to include some removal and card draw options to handle different threats. Lastly, playtest your deck regularly to fine-tune it and make adjustments based on how it performs. Good luck and may your opening hand always have what you need!