While the Pillar and Eidolon tend to be weaker in EDH overall, it seems to me that many of the favorite cards for the Urza decks are at 3 CMC or less making them perfect prey for these cards
Leafeon ex can be obtained from Triumphant Light pack in the Triumphant Light set
Honorable Mention: Ominous Harvest While Ominous Harvest does not have the mass appeal of the other cards on this list, I feel it is worth noting for the players who run multiplayer focused Cubes
Your opponents will quickly find themselves unable to compete
By itself it hits for 1 damage, then 6, and then 8 over three turns, not to mention how stupid a second copy makes it
Even though the card is designed to only do it's thing once, if we blink it while it's transformed, it'll go back to the front face, and then all we have to do to get that extra turn is retransform it