Draconic Mentorship

Dragon creatures you control gain mentor
(Whenever this creature attacks, put a +1/+1 counter
on target attacking creature with lesser power.)
Non-Dragon creatures you control are Dragonslayers in addition to their other types.
Some Dragons have been said to care for humans to
the point where they raise orphaned human children
as their own. While raising the human, they teach
them Dragon Slayer Magic.