Mill "HERO" monsters with Fusion Materials to gain large draw power with 3 copies of "Legacy of a HERO". This will also return a total of 6 HEROs to your Extra Deck, while the other 2 can be used for a Fusion Summon via "Miracle Fusion" (Or "Dark Calling", if used in an "Evil HERO" Deck).
It is also possible to mill the face-up Dragon-type Pendulum monsters in your Extra Deck, which means that "Supreme King Dragon Starving Venom" can be used in a Graveyard Dragon Power Deck containing this card. After using this card's effect for this purpose, "Supreme King Dragon Starving Venom" can then exploit the effects of the Dragons that you sent to the Graveyard.
Alternatively, you can Mill Dragon-type Synchro monsters, and then use "Converging Wishes" to summon "Stardust Dragon" from your Extra Deck, before using it and your other monsters to set off an OTK.
Note that you can destroy your own LIGHT monsters, to trigger this card's second effect. If your Zaborg the Mega Monarch destroys itself, you will send up to 8 cards from each extra deck to the graveyard.
You can use Trap Monsters or Tokens either to use as tribute fodder, or as a target to destroy in order to send cards from the extra deck to the graveyard. Obviously, these need to be light attribute to get the full effect of this card. Cards which can be used to summon light attribute trap monsters or tokens include:
Use "DNA Transplant" to change all monsters to light attribute, allowing to you trigger the effect by destroying any of your opponents monsters, or your own. You can destroy your own "Metal Reflect Slime" to select and send most, if not, all cards in their Extra Deck to the Graveyard.
Special Summon "Santa Claws" on your opponent' side of field by Tributing a dangerous enemy monster, then destroy it with "Zaborg the Mega Monarch" to send 6 monsters from your opponent's Extra Deck to the Graveyard.