Activate "The Forces of Darkness" during your opponent's turn (preferably during the Draw Phase) to return "Ceruli, Guru of Dark World" along with any "Lord of Dark World" to the hand, then activate "Dark Smog" during the same turn by discarding "Ceruli". This way you'll gain a plus from "The Forces of Darkness" (while completely eliminating its downside of being a Trap), gain a plus from the "Lord of Dark World"'s full effect and have a chance to disrupt your opponent's strategy completely.
Normal Summon (if you don't have already) a low ATK monster (like "Scarr, Scout of Dark World" or "Beiige, Vanguard of Dark World") and activate "Creature Swap". Your opponent will likely give you "Ceruli" back. Return it to the hand for a summon of "Grapha, Dragon Lord of Dark World". You can both deal a huge damage (by attacking a given monster with "Grapha") and reuse "Ceruli" again.
Use "Gateway to Dark World" during your opponent's End Phase to force him/her to discard, then bounce "Ceruli" to Summon "Grapha, Dragon Lord of Dark World" and get another chance to use its effect.
Better yet, set "Gateway to Dark World" when you know they have a means to destroy it. If you chain it to their card effect, they will get a -1, followed by an immediate -1 afterwards. When you Summon "Grapha", you gain an additional +1, for a total of +3 in card advantage off of one card in hand.
As early as you can in your opponent's turn, use "Infernity Inferno" or "Fine" to discard this card. It will be Summoned to your opponent's field and activate its effect. Discard "Neko Mane King" and your opponent's turn will end immediately.
Also if you used "Goldd, Wu-Lord of Dark World" you can destroy your opponent's other cards, while "Sillva, Warlord of Dark World" forces them to return cards from their hand to the bottom of the deck (in most cases, this is better than forcing a discard; your opponent must now regain access to the card, whereas if it's a monster and in the grave, it still can be used.)
This card is extremely powerful in conjunction with "Drill Warrior".