Aang, the Airbender

Flying, Lifelink
Whenever Aang, the Airbender attacks or blocks,
tap target nonflying creature opponent controls.
That creature doesn't untap during its
controller's next untap step.
If you have all 4 bending scrolls in play,
transform Aang, the Airbender. If you do, put a
+1/+1 counter on each human you control and
proliferate.