Right now, his Deck is just focused on swarming. It does not even begin the tip of the ice-berg of abusing Dark World. Card of Safe Return should be under no circumstances to ever be left out of the Deck. SrViper, your points are all circumstances. What if this? What if that? That is what Magic Drain is. A what if my opponent does not decide to discard a Spell Card or what if he does discard a Spell Card he/she does not need. If he will not focus on the other aspect of Dark World, then he/she needs to focus on making their swarming means something and is protected against Spell and Trap Cards, as well as removing any monster threats too strong for their Dark World monsters to handle. This is where Smashing Ground, Lightning Vortex, and so on would factor in. Using Royal Decree to stop the Traps being used against you is also a good idea but that would stop your Trap Cards and you would need them, so there comes the option of Trap Jammer or Seven Tools of the Bandit. There is so many things you can do with Dark World it is not even funny and even more absurd is how easy you can maintain a hand and field advantage with little to no effort at all.