The most likely reasons are if it's sacrificed, if it's legendary and another legendary permanent with the same name is controlled by the same player, if it's a planeswalker and another planeswalker with the same subtype is controlled by the same player, if it's a creature with toughness 0 or less, or if it's an Aura that's either unattached or attached to something illegal
Luffy Awakening of the New Era, Alternate Art, Signature ($1,933) Another Monkey D
If youre planning to pick up Battle Pack 3 just for the new cards and the chance to get some of your favorite cards as Shatterfoils, you might as well do some draft or sealed play with your friends when you open the packs
While this helps out most in tossing out Weakness by way of Altaria, there are some other tricks that might just work
The style evolved
The cool tones and fluid motion of the artwork mirror their water-type mastery beautifully