Hey fellow Planeswalkers! When it comes to deck-building in Magic: The Gathering Arena, one important tip is to maintain a balanced mana curve. Make sure you have a good mix of low-cost and high-cost spells to ensure you can play something every turn. Also, don’t forget to include some removal spells and card draw to handle different situations. Finally, always playtest your deck to see how it performs and make adjustments accordingly. Happy brewing!