Hate is an important thing to remember when you’re building an EDH deck. This may seem odd, for such a social format, but sometimes it pays to hate out certain anti–social strategies. Graveyard hate is the most commonly included, because it’s easy for any black deck to toss in a Bojuka Bog and call it a day. But even beyond the Bog, it’s easy to justify playing Nihil Spellbomb or Relic of Progenitus in your deck, because these cards not only solve a problem, but they cantrip as well.
Still, sometimes it’s worth throwing in a sideboard card to keep yourself safe from certain combo or value strategies. Some of these anti–combo cards aren’t going to do much on an empty board unless you have wider synergies. Grafdigger’s Cage and Torpor Orb are both great cards, but unless your deck has some synergy with artifacts (like, say, through metalcraft, affinity, or one of the Tezzerets) these cards are going to do nothing to advance your board position. It might be worth it, however, to shut down the Mimeoplasm player’s Dread Return, or to keep the deck full of Mulldrifters from quickly overwhelming everyone with incremental card advantage.
Some hate cards are too mean, though, to keep you from drawing a non–proportionate amount of aggro in response. I’m talking about cards like Blood Moon and Magus of the Moon, that turn off most multi–colored manabases. This is also true of classic cards like Meekstone, which turns off most creature strategies, or Stasis, about which there’s been some new chatter since it’s the only card that has any real synergy with Urban Burgeoning. Playing these cards are the equivalent of playing a deck full of Armageddon effects; it might do what you want it to do, but they’re not going to make you any friends.
So, it’s best if your hate cards are utilitarian and not so disruptive as to turn the whole table against you. For this purpose, I like flexible removal spells. The charm cycle has been great for this. Rakdos Charm manages to take care of a problem permanent type (artifact) while also having the ability to nuke any troublesome graveyards. I also like Mortify and Putrefy, because they’re both instant speed answers to creatures and an additional permanent type. Green has a host of utilitarian effects, but I am a particular fan of two of them: Woodfall Primus and Rain of Thorns. The Primus is known to be an excellent card, but it’s worth trying out Rain if you haven’t yet; this unassuming uncommon from Avacyn Restored not only takes out a variety of permanent types, but it can take out three problem cards at once, none of whom need to share a controller.
There’s also a whole host of effects that are good on their own, but scale to stop certain combos in their tracks. The best example of this are your Propaganda effects, including Ghostly Prison and new friend Sphere of Safety. Against any generic creature deck these effects are worth playing; they disincentivize other players from attacking you without drawing a particularly large amount of aggro. It is against decks with Kiki–Jiki or Splinter Twin combo finishes where these effects shine. Unless they also have a way of making infinite mana, these combos aren’t going to be able to take you out with the rest of the table. Another card I like for this sort of versatility is Loaming Shaman. He’s a solid guy to have on the table in the best of times, but he excels against the Mimeoplasm’s self–mill strategies (like Mirror–Mad Phantasm) as well as Vendilion Clique’s Tunnel Vision plan. He’s not all that threatening on his own, but he can sure save you in a pinch.
Finally, let’s talk about retributive hate cards. These are your Karmic Justices, your Marytr’s Bonds and your Grave Pacts. The key with this card is both not over–exploiting the effect (say by using Awakening Zone to make all your opponents sacrifice a creature each turn) and being wise about when to not be a jerk with any targeted effects. I was playing in a game once where my partner was hiding behind a wall of enchantments and Karmic Justice, when one of our friends cast Planar Cleansing (a surprisingly useful wrath for those situations where Austere Command just doesn’t kill enough). Dana got a ton of Karmic Justice triggers out of the situation, which had bombed several of our friend’s permanents as well, and she targeted each one of our friend’s lands. Our friend was out of that game at that point, for the temerity of having a board wipe effect, and the worst part was it took a fairly long time for Dana to actually get around to leveling the killing blow. It was unpleasant, and no fun. So, just recognize there are going to be situations where getting the most out of your triggers is going to conflict with not being a terrible player in a group environment.
Commander is the type of format in which you might see all sorts of random combos fighting alongside creature decks that just try to beat face with large dudes. Usually, it’s worth having an effect in your deck that you’d be playing in your sideboard in any other constructed format. And, if the effect can stop a combo while being good on its own? It’s definitely worth looking at when you build.