Burst Lightning
It takes a concept (a species in danger of vanishing from the earth) and melds its mechanics to fit that idea (the creature literally has vanishing, but you can stop it if you take the right actions)
I acquired it in an elaborate trade and my plan is to hold onto it indefinitely
Chromatic Lantern - Lets your lands tap for any color as well as tapping for any color itself, this is a great ramp card as well as land fixer
From here on out, I keep the multicolor, lands and tokens sorting as the final part of the sorting process
This may find its way into Zombie decks that flood the board very naturally - Wilhelt, the RotcleaverWilhelt, the Rotcleaver, to be specific - but in my opinion, Zombie strategies are another extremely well-established archetype, so it's hard to make room for cards like this, even when they look really cool