We still have not reached a definitive conclusion to this discussion, so does anyone have any further feedback to provide?

My Jenara deck contains a copy of Commander's Sphere, which is a good card, but I could remove it, so that I can put both Smothering Tithe and Esper Sentinel into that deck; what does everyone else think about that?

KibaAlpha, Luminarch Ascension is nice, but I realized that it does not fit the general theme of the deck, since it is better in control/pillowfort decks, whereas this deck is focused more on combat, so it will be to this deck's benefit to replace it with another card.

On the other hand, does this deck have sufficient mana acceleration? It contains seven mana-generating artifacts, which is good, but Smothering Tithe would provide another source of mana acceleration, which is never a bad thing.

shaftdiggity, what about Mind Stone or Decanter of Endless Water? They are also a form of ramp/mana acceleration.

Niko9, since Esper Sentinel is a creature, it can attack and block, and this deck does have a combat theme; it is redundant with Rhystic Study, but redundancy is a good thing, in this case.

Abaques, that is very good, so I shall keep it in mind, although I shall wait for several more days, to see if any other users respond, before I make a decision.

I am sorry for the triple post, but does anyone here have any suggestions? I was hoping to have a meaningful discussion of this subject.

DreadKhan, those are definitely great suggestions, but I am actually planning to remove Luminarch Ascension from this deck, rather than keep it and find ways to make it easier to use, because that card draws the ire of other players. At this moment, I am deciding between Smothering Tithe, Windborn Muse, or Esper Sentinel; which of those three cards do you think is best to replace the ascension?

Abaques, that is no problem, at all, since you made an excellent point; I have a copy of Silent Clearing in an EDH deck with Liesa, Shroud of Dusk as the general, because that deck has such a great amount of life gain that the payment for using the land is almost inconsequential (plus, the deck also contains a Chromatic Lantern, which allows the land to produce mana without paying life), but not all of my decks would be able to continually pay life to produce mana.

Not to be annoying, but does anyone have any feedback for me regarding this subject?

For those users who are suggesting that I use the "pain lands" (i.e., Battlefield Forge, Caves of Koilos, and so forth), I will not use those lands in the majority of my decks, since most of my decks cannot afford the constant damage/loss of life; I will gladly take the (minuscule) chance of my lands entering the battlefield tapped over the constant danger of hurting myself when I need mana.

I have a copy of Luminarch Ascension in my Jenara, Asura of War EDH deck, because I think that it is an awesome card that can quickly produce a massive army of tokens if it is left unchecked, but that same reason will also make its controller a major target, and it is highly unlikely that their opponents shall simply allow that card to reach its fullest potential, so I am contemplating removing it from that deck, and replacing it with another card.

At this moment, I am considering either Smothering Tithe, Windborn Muse, or Esper Sentinel as replacements for it, since each of those card is an excellent card in its own right, although there could be another card that would be even better for that deck.

What does everyone else say about this? Should I replace Luminarch Ascension, and, if I do, with which card should I replace it?

I ultimately have chosen Rhystic Study, so I thank everyone for their feedback.

I have replaced Luminarch Ascension with Black Market Connections, which, unfortunately, increased this deck's average converted mana cost from 4.05 to 4.06, but I believe that that increase is absolutely justified by the amazing value that BMC shall provide.

After asking the other users here for advice, I have replaced Ring of Three Wishes with Rhystic Study, which decreased the average converted mana cost of this deck from 3.90 to 3.87, which is very nice.

I have replaced Smothering Tithe with Black Market Connections, which decrease this deck's average converted mana cost from 4.08 to 4.06, because, as great as the tithe is, I need it for another deck, which does not include black, and the connections were less expensive than is the tithe; plus, BMC is too awesome for me to not put it in at least of my decks; this deck should have a sufficient amount of life gain to justify its inclusion.

I have replaced Seaside Citadel with Spara's Headquarters, since the latter card can be found with Wood Elves.

I have the shock lands in all of my decks (both EDH and 60-card), since they are the best dual lands available, given that the original dual lands are insanely difficult to obtain, and I also have the "check lands" (i.e., Glacial Fortress, Isolated Chapel, and so forth) in all of my decks, as well, because they are possibly the third-best cycle of dual lands in the game (although I feel that the "filter lands" may be a competitor for that title). For two-colored decks, the check lands will consistently enter the battlefield untapped (I honestly cannot recall the last time that they entered the battlefield tapped), but, in decks of three or more colors, they are less consistent; I would say that they enter the battlefield untapped anywhere from seventy-five to eighty percent of the time, but the few time that they enter tapped have proven to be very disadvantageous to me.

Therefore, with the printing of a new cycle of dual lands in the third Innistrad block, which most players are calling the "slow lands" (i.e., Shattered Sanctum, Deathcap Glade, and so forth), I am considering replacing the checklands in my decks with three or more colors with those new lands, since I feel that they are a better option.

What does everyone else say about this? Should I replace the "check lands" with the "slow lands?" Also, as long as I am asking that, it is obvious that the "filter lands" (i.e., Cascade Bluffs, Rugged Prairie, and so forth) are great for two-colored decks, but how are they in three-colored decks (I do not have them in my four- and -five colored decks)? What are your opinions on this matter?

lukas96, that is now three votes in favor of Rhystic Study, so, unless more users vote for Smothering Tithe by this upcoming Saturday, I shall put RS into my deck.