It isnt the case that untapped creatures can never attack, but a creature is usually tapped if it is attacking
Remand (7.5), Negate (7.5), and Arcane Denial (8) are among the most commonly seen in these lists as they are relatively cheap and far easier to play in decks lighter on the blue
Creatures (13) Planeswalkers (1) Lands (20) Spells (26) Creatures (12) Planeswalkers (2) Lands (18) Spells (28) In fact, if certain other cards, such as Urza, Lord High Artificer or Oko, Thief of Crowns find their way onto Moderns ban list, its entirely possible that Once Upon a Time will become ubiquitous enough to earn itself a ban on the grounds of making green decks too consistent
The most important thing to me when analyzing formats is the edge and appropriateness of a deck when contextualizing to a particular format
2) Charizard ex Charizard ex, once set up, can deal phenomenal levels of damage
This gold-background Ns Zoroark ex exemplifies how misprints can elevate a collectible card to a highly prized possession