When Goblin Zombie is sent from the field to the Graveyard, you can search Vampire Dragon from your Deck and add it to your hand since it has less than 1200 defense. You can also use it as a tribute for Vampire Dragon and its effect will activate.
Adds from Deck to hand / Activates from your Graveyard
This lets you tutor a lvl 4 of your choice on death? Very nice.