In general, rare cards from older sets are often more valuable than newer cards
Outside of running a compliment of Counterspell's, Im inclined to go the route of cards like City of Solitude, Dosan the Falling Leaf, Teferi, Time Raveler and Teferi, Mage of Zhalfir forcing most if not all players at the table into the same tempo of game play
Its in blue/green and has a graveyard ability
While this wont always come up, its nonetheless nice to have, especially following the recent release of the Planeswalker Party deck
The set, including the Turtle Power
The other option will be to wait for the spike when everyone knows about the cards, not just the folks who are rabid for new news and are invested in being on top of the newest information