4 Knights , 1 Questing Beast and maybe a Tireless Tracker
Winter Orb was used most abusively in actual Prison decks that used Icy Manipulator and other tap effects to deny you even the one untap that Winter Orb gives you
Emboar - 20/114 Non-Holo Promo - World Championships Promo - World Championships 2011 World Championships NM/M Value: 0.72 Energy Retrieval - 92/114 Non-Holo Promo - World Championships Promo - World Championships 2011 World Championships NM/M Value: 0.89 Engineer's Adjustments - 75/95 Non-Holo Promo - World Championships Promo - World Championships 2011 World Championships No Data Yet
On a negative note, Skarmory is indeed a Mega Evolution, which comes with the clear risk of giving a lot of advantage to your opponent if it falls in battle, so that is the entire reason why I didnt dare include it higher on the list
However, there is a simple, digital solution that could solve all our problems
Perhaps even more interestingly, we could see Station as a new way of leveling up permanents you control