I started with my Ezuri deck. When it came back a 7, I thought "well that seems low; maybe they allowed a lot of room for competitive decks?" So, I put in the Momir-Vig hackball cEDH list. When that was a 7, I knew the thing was broken, but I wasn't sure how broken. The last deck I put in was my Omnath lands deck I play against precons.
It was then I realized I was the April Fool.