Note that despite the fact that this card has tricky summoning conditions, you can still Normal Summon it without a tribute if you lower its level with something like "Star Blast", since it only places restrictions on Special and Tribute Summoning.
Malefic Deck can do the same because all of them are easily searched and special summoned high level DARK monsters.
You can use "DNA Transplant" to overlook the fact that "Diabolos" needs DARK tributes.
This card's effect that lets you see the card your opponent will draw is a very good advantage when you have an active "Deck Devastation Virus" or "Eradicator Epidemic Virus". You can manipulate his/her Draw Phase, by allowing him/her to draw the card that will be destroyed depending on the active virus card.
Dark World Can provide easy tributes for this card, as well as for "Viruses".
The effect to control your opponent's draw gives you a huge advantage, especially against a Lightsworn and Dark Armed Dragon decks and players who like to stack their deck.
Use "Fires of Doomsday" at the end of your opponent's turn, to summon this card in your turn.
Use this card in tandem with something that lets you look at your opponent's hand so you can determine whether or not you should let them draw their next card.