Praetor's Counsel should be included for the power of mass recursion and unlimited hand size.

As mentioned in comment 261, I think Burnished Hart is actually a pretty great ramp card for colors that don't normally get too much of it (looking at you, red and blue). It's also pretty cheap, moneywise, so it's good for budget players.

Also, Nykthos, Shrine to Nyx seems like a good card for mono-colored EDH. Staple? Maybe. Power card? Probably not. Worth testing, at least.

What about Hellkite Tyrant ? It provides an alternate win condition and steals artifacts, which are both awesome on a 6 CMC creature in EDH. That said, it's very much a "build around me" card that can conflict with commanders. For those running decks with both red mana and lots of artifacts, though, I feel it's a pretty strong inclusion. Especially if you're trying to force a response.

Strange that Misdirection and Trickbind aren't on here.

I'm gonna have to say Witchbane Orb would be an EDH power card. Being hexproof is a huge advantage against decks that otherwise would burn you or cause you to sac something.

This list is very useful. Thankyou!

how about True-Name Nemesis ?

@ms: True-Name Nemesis is bad in EDH. It's just a 3/1 beater.

if you pump it with swords, enchantments and equipments...

That means you need to run a lot of cards to make a 3/1 viable. It's not a good strategy, and True-Name Nemesis is weak overall. Especially when you consider that the format is full of wipes.

Triskelion ? Why is he not on the list?

@Human_Rogue_21: Triskelion is neither a staple nor a power card. It's only good in combo decks, and only a few even play it.

Jeez, most of the cards I was going to suggest are already on the list. I guess that means I'm doing something right. These are my suggestions.

//////////////////////////////////////////////////////[Creatures]///////////////////////////////////////////////////////////////

Birds of Paradise : A fantastic way to start a game or to get the right color(s) for a multicolored deck.

Eternal Dragon : Being able to grab a plains (or shockland plains) for two colorless seems like a good way to thin out a deck consistently along with his Disentomb ability.

Kalonian Hydra : This guy can really wail on someone. Getting bigger and bigger and naturally having trample is a huge bonus.

Serra Ascendant : Immediately a 6/6 flier for W can really put the hurt on someone early on, and gaining 6 life per swing is something I can't really complain about.

Steel Hellkite : One of the best (in my opinion) removals on a stick.

Tsabo Tavoc : A nightmare for anyone even thinking about using their commander. Having protection from all legendary creatures along with being a 7/4 first strike makes him very useful to have on the field.

////////////////////////////////////////////////////////[Sorceries]//////////////////////////////////////////////////////////////

Curse of the Swine : Since it exiles creatures, I feel like it's too good to not have. It can be very comforting knowing that you'll never have to see certain creatures again.

////////////////////////////////////////////////////[Enchantments]//////////////////////////////////////////////////////////

Darksteel Mutation : I would say removal on the level of Oblivion Ring since it can be destroyed (and is only for creatures) but the pros of making the creature lose all abilities and become an indestructible 0/1 outweigh the cons.

Oops. Didn't see your earlier reply. Makes sense about Kalonian Hydra . He does take a couple turns to be really effective.

Tsabo Tavoc as she is one mean anti any commander deck as she destroys other legendaries. Well except for those indestructible or hexproof kind.

Rise of the Dark Realms as in EDH games the graveyards get quite hefty. Won quite a number of games with this, especially when pulling an Avacyn, Angel of Hope and a Platinum Angel out of the grave.

Relic of Progenitus to counter the aforementioned card and other similar strategies.

Demonic Collusion is a great tutor card due to its reuse if your hand is continual crap.

Veteran Explorer and Gather Specimens

@supercaptainpow:

Eternal Dragon seems kind of clunky. I don't know that the plainscycling really justifies it. Do you have game experience with this card?

I discussed Kalonian Hydra earlier. I don't like that it's so clunky and only functions as a beatstick.

I've been hesitant to include Serra Ascendant , but I suppose it can make the list.

@RyProv: I'm hesitant to include Demonic Collusion . It seems mediocre. Have you had game experience with it?

@Kozelek: Gather Specimens is rather expensive. I don't know that I would call it a staple or a power card. It's certainly neat, and it can pull some hilarious tricks, but I don't know if it belongs on this list.

How about Elspeth, Sun's Champion , Hero's Downfall or Spear of Heliod ?

@KingSorin: Elspeth, Sun's Champion seems underpowered in EDH. Same with Spear of Heliod (and retribution effects in general).

I thought killing all the fatties at the table or generating heaps of blockers would be considered powerful... Anyway, you know more about this than i do. :)

Does Opal Palace warrant a spot?

@KingSorin: I'm open to second opinions. Maybe somebody with play experience will chime in. From a theoretical standpoint, I can see both sides.

As for Opal Palace , I don't personally think it's good enough. It's a filter, and the ability doesn't really net you all that much advantage. At least, not enough to warrant running Opal Palace over some other land.

Crop Rotation and you need to delete a bunch of old comments so ppl like me on ipods dont need to spend 3 min scrolling down to comment lol

Perhaps Phyrexian Processor I use it in my commander decks it allows me to pop out intimidating minions at a relatively low life cost, also Mirari any deck that does controlling or spell casting can cast huge spells again such as Army of the Damned

@Kozelek: Crop Rotation doesn't seem all that critical. It's a nice utility spell, but it hasn't been prevalent in most of my games. What;s your experience with it?

Also, I hesitate to delete older comments because I like there to be a record of the discussion. I suppose I could hide them under an update; people probably won't even read them.

@kameenook: Phyrexian Processor and Mirari are okay, but they aren't staples, and they don't really qualify as power cards because they're limited in utility and prevalence.