Amaru Squire

Promote (Whenever another creature you control leaves the battlefield, if that creature had greater base power than this creature's power, put a +1/+1 counter on this creature.)
When Amaru Squire enters the battlefield, create a 2/2 white Human Knight creature token with vigilance.
As long as Amaru Squire has been promoted,
it's a Human Knight and it has vigilance.