Whoah, whoah, whoah! You guys have forgotten some spells! Late game, there's Boundless Realms (fantastic deck thinning, but only good if your run a lot of basic lands, obviously). Then, there's some non-green ramp: Druidic Satchel (it's not reliable, but has potential, especially if you run top-of-the library manipulation like Sensei's Divining Top) and Explorer's Scope (I realize this is worse than Druidic Satchel cause it might not actually end up doing anything, and you have to attack to activate it and there might be times when you don't want to attack, so I'd only recommend this for a token deck or something with expendable creatures)
I'm not sure why no one else has mentioned this, but Felidar Sovereign seems like an obvious choice here. Being 6 mana shouldn't be an issue in edh and it's a creature, so it can attack and block, and it has lifelink itself! Also, since you are mono-white, Emeria the Sky Ruin seems like an obvious card. I mean, you get to get back creatures for free doing nothing but playing a land! EDH games tend to go long, so trust me, you will get 7 plains out.
First off, take out all the mass land d you have in here. Ruric doesn't combo with mass land d at all. If you were running Kaalia of the Vast, well I can see that. Also, imagine this: suppose you blow up all lands, but in response, someone kills Ruric. Congratulations, you have now stalled the game and EDH is already a format that is slow. Plus, everyone else is pissed at you for blowing up their lands and will gang up on you, and prob not want to play magic with you again.
Secondly, I would run ONLY creatures (unless for someone reason, you want to take 6 damage). That being said, you will be lacking in mass removal. However, I would run any and all creatures in your color that can serve as removal. For example: Duplicant, Steel Hellkite, Ulamog the Infinite Gyre (because when you cast him), Inferno Titan (repeatedly kills weenies), Gruul Ragebeast. If you want ramp, there are creatures that can do this: Solemn Simulacrum, Farhaven Elf, Wood Elves (which can help you find the dual/shockland), Yavimaya Dryad, and the list continues. Card draw is also important, so I would run Ohran Viper
Thirdly, if you do not run ANY noncreature spells, these guys will be VERY good to run: Nullstone Gargoyle, Heartwood Storyteller, and Drumhunter (your general will probably always be out there, so this is a free card every turn). I considered Thorn of Amethyst, but taxing people by only 1 mana isn't very effective. If you are only running creatures, then these guys are worth considering: Primordial Sage, Somberwald Sage, and Soul of the Harvest.
Finally, you need to make sure each creature that you run is a valid threat ON ITS OWN. What I mean by that is, assume that you have just lands and that creature on the battlefield and ask yourself the question: is this a creature my opponent will want to get rid of immediately, or gives me some benefit/gets rid of a threat when it enters the battlefield? If the answer is no, take that creature out. So, I would remove these creatures: Sylvan Safekeeper (setting yourself back a land is not worth it. Just run more threats. Also, the only 1/1s that can be threatening in EDH is Scute Mob and Dragonmaster Outcast. Other good 1/1s are utility guys, like Elvish Piper), Keldon Firebombers (again, take out the mass land d), Azusa (this creature is only good if you build an entire deck around it. Consider Oracle of Mul-Daya, which is very good on its own), Godo (if you decide to not run any creatures), Dragon Mage (giving your opponents cards is BAD).
I seriously can't believe no one has mentioned this, but: Devout Witness. Any card in your hand is now a disenchant. Might I mention..you can do this repeatedly! Oh, and it also works well with dredge, reanimator, madness, etc.
Some new cards have come out and I have a mono green edh and the removal that I run are:
Brittle Effigy
Duplicant
Argentum Armor
Spine of Ish Sah
Karn Liberated
Desert Twister
Beast Within
Tornado
Arena
Predator, Flagship
Prey Upon
Triangle of War
Ulvenwald Tracker
Also, Heartseeker and Predatory Urge is an option (but I didn't put it in the list above since it doesn't fit my edh deck).
Finally, I want to add that I strongly recommend Karn Liberated for his -3 effect. After all, what other monogreen/colorless card can deal with a darksteel forge or darksteel plate? (Answer: Splinter and Amulet of Unmaking)
I finally realize the point of Gideon's ultimate: you play him in a turbo fog deck until he gets to the ultimate (also hold on to some lands in your hand, since the ultimate gets rid of lands too). Then, you float a bunch of mana, use his ultimate, then use the mana you floated to drop a bomb, which your opponent will most likely not be able to answer since your opponent will have no lands or nonland permanents on the battlefield (but your opponent could topdeck a plains and a swords to plowshares or path to exile, so to avoid that, just drop a bomb that has shroud/hexproof). However, I did think of a convoluted way to make Gideon's ultimate work while saving all your permanents: 1) get Gideon to 15 counters, 2) play Upwelling, Leyline of Anticipation, and Taniwha, 3) on a turn where your land would phase out on your upkeep due to Taniwha, float a bunch of mana in response (upwelling lets you carry that mana to your main phase), 4) use Gideon's ultimate, and in response to the ultimate ability on the stack, cast Sudden Disappearance (the leyline allows you to cast this at instant speed). If you don't need lands to win after this combo (because you'll prob have a bunch of beaters on the battlefield), then Upwelling and Taniwha aren't needed (the leyline would be replaced by vedalken orrery, and you just do the ultimate and play sudden disappearance in response). Granted, the combo I just mentioned requires 5 cards, which is extremely cumbersome to pull off.
Secondly, I would run ONLY creatures (unless for someone reason, you want to take 6 damage). That being said, you will be lacking in mass removal. However, I would run any and all creatures in your color that can serve as removal. For example: Duplicant, Steel Hellkite, Ulamog the Infinite Gyre (because when you cast him), Inferno Titan (repeatedly kills weenies), Gruul Ragebeast. If you want ramp, there are creatures that can do this: Solemn Simulacrum, Farhaven Elf, Wood Elves (which can help you find the dual/shockland), Yavimaya Dryad, and the list continues. Card draw is also important, so I would run Ohran Viper
Thirdly, if you do not run ANY noncreature spells, these guys will be VERY good to run: Nullstone Gargoyle, Heartwood Storyteller, and Drumhunter (your general will probably always be out there, so this is a free card every turn). I considered Thorn of Amethyst, but taxing people by only 1 mana isn't very effective. If you are only running creatures, then these guys are worth considering: Primordial Sage, Somberwald Sage, and Soul of the Harvest.
Finally, you need to make sure each creature that you run is a valid threat ON ITS OWN. What I mean by that is, assume that you have just lands and that creature on the battlefield and ask yourself the question: is this a creature my opponent will want to get rid of immediately, or gives me some benefit/gets rid of a threat when it enters the battlefield? If the answer is no, take that creature out. So, I would remove these creatures: Sylvan Safekeeper (setting yourself back a land is not worth it. Just run more threats. Also, the only 1/1s that can be threatening in EDH is Scute Mob and Dragonmaster Outcast. Other good 1/1s are utility guys, like Elvish Piper), Keldon Firebombers (again, take out the mass land d), Azusa (this creature is only good if you build an entire deck around it. Consider Oracle of Mul-Daya, which is very good on its own), Godo (if you decide to not run any creatures), Dragon Mage (giving your opponents cards is BAD).
Brittle Effigy
Duplicant
Argentum Armor
Spine of Ish Sah
Karn Liberated
Desert Twister
Beast Within
Tornado
Arena
Predator, Flagship
Prey Upon
Triangle of War
Ulvenwald Tracker
Also, Heartseeker and Predatory Urge is an option (but I didn't put it in the list above since it doesn't fit my edh deck).
Finally, I want to add that I strongly recommend Karn Liberated for his -3 effect. After all, what other monogreen/colorless card can deal with a darksteel forge or darksteel plate? (Answer: Splinter and Amulet of Unmaking)