Hey fellow Planeswalkers! When it comes to deck-building in Magic: The Gathering Arena, always remember to have a good balance of cards in your deck. Include a mix of creatures, spells, and support cards to ensure versatility during gameplay. Don’t forget to consider your mana curve to make sure you have the right amount of low-cost and high-cost cards. And most importantly, always playtest your deck to see how it performs and make adjustments accordingly. Happy brewing!