Using "Ultra Polymerization" will cause you to permanetly lose your Fusion Material. This is because Konami ruled that it has to Special Summon monsters that still match the listed Fusion Materials, and "2 DARK monsters on the field" logically cannot be in the Graveyard.
"Predaplant Chlamydosundew" can be used to allow this card to be Fusion Summoned by using an opponent's monster with a Predator Counter.
If you Fusion Summon this card with "Flash Fusion", it will be destroyed during the End Phase, allowing you to wipe out your opponent's Special Summoned monsters. Since "Flash Fusion" is a Quick-Play spell, you can do this on your opponent's turn.
You can use "Witch of the Black Forest" and "Sangan" to Fusion Summon this card instead of "Sanwitch". Not only will you have gained a powerful DARK Monster, but you will have added two new monsters from your Deck to your hand.
In an Exodia Deck, you can Fusion Summon them on your turn with another card, adding two "Forbidden One" cards to your hand.
Appropriately, this card is particularly useful against "Odd-Eyes Pendulum Dragon", as it can copy that monster's effect and possibly cause an OTK, which can be backed up if "Starving Venom" was Fusion Summoned on this turn, allowing it to gain a opponent monster's ATK.
You can use "Shien's Spy" to give "Odd-Eyes" to your opponent, and beat 5600 damage into your opponent.
After Fusion Summoning this card, destroy it with "Destruct Potion", and use "Starving Venom's" effect to destroy your opponent's Special Summoned monsters, with the added benefit of gaining at least 2800 LP.
You can use the effect of "Darklon" to make all your monsters become eligible Fusion Materials for this card.
Since DARK is an extremely popular attribute among monsters, this is one of the easiest cards to summon with "Super Polymerization".
If this Fusion Summoned card is destroyed by the Flip effect of "Cyber Jar", then the Monsters your opponent Special Summoned with its effect will be destroyed.
In a Dragon Deck, select this card when you activate "Last Turn". If it is destroyed, your opponent's Special Summoned Monsters will be destroyed along with it. "Keeper of the Shrine's" effect can be chained to this card's, leaving you as the sole player controlling Monsters.