The Last Dragonborn

Dovakiin -- The Last Dragonborn gets +5/+5 whenever it blocks or becomes blocked by a Dragon.
When The Last Dragonborn enters the battlefield, it deals 5 damage to all Dragons.
{1}{r}{u}: The Last Dragonborn deals 3 damage to target creature and that creature can't attack or block until end of turn.
{1}{g}{g}: The Last Dragonborn gets +3/+3 and gains reach and trample until end of turn.