mtg whenever a card is exiled Magic: the Gathering - Rhys The Whenever Assimilation Aegis becomes attached to a creature Pojo's Magic The Gathering Card

Most cards can only attack or use their abilities once per turn, and tapping the card is how you show that this once-per-turn power has been used up

Just look at this flavour text to the red-aligned Urabrask the Hidden

The graphic they added to the Mystery Booster packs had a square background, and the one they used for The List seems to have a rounded background, which creates a telltale difference in the shape of the cards border as you can see on Chatter of the Squirrel and Ancient Den as well as subtle changes in its placement on new border cards, as seen on Boros Challenger

Of course, that means youll only find one Enchanted card in every three boxes, if youre lucky

And bonus I can run nonsense like Relic Amulet and Sphinx-Bone Wand to damage Dralnu myself once I donate him