Didact Echo

The cantrip body is the constant here; the flying is the variable you have to earn. Draw-a-card-on-enter has been blue's baseline value staple for as long as the color has existed, and a 3/2 that replaces itself is honest filler on that count alone. What the design layers on is a graveyard threshold that flips the same creature from a ground-stuck body into an evasive clock once four permanent cards have piled into your yard. It is a conditional keyword rather than a stapled one: the flying comes and goes with the state of the graveyard, so a board wipe that refills your yard or a self-mill turn can switch it on, and a graveyard hate spell can switch it back off. That toggle is what separates it from the older run of blue value bodies that either flew or did not from the moment they resolved. The descend mechanic ties the reward to a deck already invested in filling its graveyard, which means the flying is close to free in the shells built to want it and close to irrelevant everywhere else. As a piece of construction it is deliberately backloaded: the card pays you immediately for the cantrip and then pays you again, later, if the game goes the way its home deck wants it to.