Defining a Hybrid Set in Eventide

There was a card that inspired this mechanic, which you designed back in eventide. Was a mechanic where you could pay manna and a the creature had three different sort of text boxes and power, toughnesses. You could upgrade the creature by spending manna and id sen ro quickly,. case the magic historian me has to bring something up. At flying first rike it was the early version of what this mechanic would be - although it didn't have all the frame changes in stuff.