What are the best strategies for building a competitive deck using party cards in Magic: The Gathering?

To build a competitive deck using party cards in Magic: The Gathering, focus on synergy between different party types, include a mix of creatures and spells that support your party creatures, prioritize cards that provide card advantage and removal, and consider the overall mana curve and balance of your deck. Additionally, include cards that can disrupt your opponent's strategy and adapt your deck based on the current metagame.