Keyword: Mentor

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Truefire Captain is dealt damage, it deals that much damage to target player.

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
When Light of the Legion dies, put a +1/+1 counter on each white creature you control.