The heart of magic cube is designed first and foremost to be accessible and emulate the feel of a classic limited environment. That means purposefully designing with the following principles in mind

• Reading the card should explain the card
  • Mechanics should be evergreen or have reminder text
  • Cards should be easily understood on a single read through
  • Modern rules formatting is prioritized (i.e. "removed from the game" vs "exile" and "any target" vs "target creature or player")
• Wordiness should be carefully weighed relative to what it adds to the gameplay
  • Trinket text should be avoided when possible
• External game pieces should be excluded (i.e. The Monarch, City's Blessing, and -1/-1 Counters)

• In general, cards should be around or under 1 USD
• When possible, less expensive cards should be used over more expensive counterparts

• Games should be generally defined by the accumulation of player decisions (i.e. combat, card selection, tapping out vs holding up mana) rather than being warped around individual cards (i.e. planeswalkers and other "bombs")

• Nonland cards are meant to emulate the power level of a classic limited environment
  • Instant speed card draw has been intentionally restricted
  • Creatures have been selected carefully to balance between casting/deckbuilding requirements, card advantage, and board impact
• Lands and other fixing is intended to encourage 2 color decks and allow 3+ color decks.