The Pokmon Trading Card Games official tie-in with Niantics Pokmon GO mobile game included cards with a peelable face that revealed a Ditto hiding underneath
Counterbalance could reveal Destined to Lead and counter both Negate and Mindbreak Trap
For both of these promo cards, the non-glossy versions are roughly 10x-100x easier to grade as well because of non-glossy card stock, better centering, and no common edge damage from peeling from the corocoro comic
if the Pokmon Spike Energy is attached to is in the active spot and is damaged by an opponent's attack (even if it is KOd), you get to put two damage counters on the opponents attacking Pokmon
This lets you manipulate the battlefield by keeping your opponents in the dark anytime you attack, never knowing what is under the face down creature coming their way
Elenda, the Dusk Rose [Best Vampire Commander for Sacrifice Decks] Elenda gets bigger every time something dies, and when she finally exits the battlefield, she floods the board with Lifelink Vampires equal to her power easily one of the best Vampire Commanders MTG has for aristocrats that just wont quit