Enchantment land cycle, missing a card

[Titanium Dragon]

I'm making a cycle of enchantment lands for my North American Native American themed set. I came up with four, but the fifth one I still don't like. They exist as enablers for the Great Circle theme of the set, where you get some bonus for having an artifact, a creature, an enchantment, and a land in play simultaneously. The red one helps support the Weave mechanic of the set, a mechanic which reduces the cost of a spell by 1 for each spell currently on the stack.

The four I like are as follows:

Clouded Peak
Enchantment Land
(Clouded Peak isn't a spell)
Whenever you play a spell, add R to your mana pool for each other spell on the stack.

Magical Vale
Enchantment Land
(Magical Vale isn't a spell)
At the beginning of each of your main phases, add G to your mana pool.

Sparkling River
Enchantment Land
(Sparkling River isn’t a spell)
At the beginning of each of your opponent’s main phases, untap target land.

Windswept Plains
Enchantment Land
(Windswept Plains isn't a spell)
At the beginning of your precombat main phase, choose an opponent. Add W to your mana pool plus an additional W for each land more than you that opponent controls.

I'm looking for a land for black, as well as feedback as to these four. The black one needs to not tap to add mana to the mana pool and to be thematically black. Anyone have suggestions/feedback?

[Harlequin]

As far as balance, I think these lands are all pretty busted, esp if you had multiples in play. 

The Red one is probably ok - but with 2 or 3 in play, this could be a big problem.   Lets say you have two of these in play, A lava Dart, a Fireball, and a Chain lightning.  So you cast CL the ability triggers twice.  RR, now you cast Lava dart before CL resolves RRRR+RR-R, Now flash it back.  RRRRR+RRRR = 9 red.  So you get 3+1+1+9=14 dmg for basically 1 mana, and 2 lands.

The white one seems fairly terrible.  If you have no way to spend the mana (instances or instant abilitys) then you could have a serious mana-burn problem on your hands.  It would probably not see play.

The green one always gives you 2 mana, never more, never less - and you have to split it up.  And you can't avoid the mana burn if you can't spend it. 

This is strictly worse than the Blue one which alows you to not only add extra mana - but avoid the burn.  And if you may have the option to untap Rav bounce lands, or Gaea's cradle or something that taps for more than one.  Lastly, the "blue" one can litterlly be splashed into any deck with lands, you could add this to mono-red burn and draw benefit.  Which means in any deck that would run the green one - you would be better off running this one instead.

"busted" but balanced with the others:
Burial Grounds
Enchantment Land
(Burial Grounds is not a spell
Whenever a creature you control is put into the graveyard from play, add for each creature in your graveyard.

Probably would be fine as:

Whenever a creature you control is put into the graveyard from play, add to your mana pool.

[andrewpate]

I don't see your example using the red one as a real problem, since it requires multiple copies in a deck which appears to have been built around the land.  Is that really more broken than the "Izzet Spike" combo from Kamigawa/Ravnica Standard?

The green one seems fine to me, for the exact manaburn reason you point out.

The "blue" one is obviously a problem for the simple reason that it is, as you point out, in no way tied to blue.  Any deck with instants wants to run several copies.  What if it added whenever an opponent plays a spell?  It would still help you use CA instants and countermagic.

The white one I think I'd have to test a little.  Obviously not just any white deck will run it, but could something be built, say in Extended, with 4xChrome Mox, some Coalition Relics, like 10 lands, and this?  Light control elements on the front end, big mana sinks on the high end.  But the fact that I'm thinking about might make it okay in and of itself.

The black one you suggest does obscene things with 2xNether Traitor and other such things, and it turns Basal Sliver into an obscene mana mill.  I could see a deck with lots of creatures with sack effects, Skulltap, Night's Whisper, and that land coming up in Extended.  Come to think of it, that sounds like a lot of fun, and easy enough to disrupt that it should be acceptable.  It might also have a place in some kind of combo Goblins or even in Vintage Kobold combo (the deck's big break!).  All of that, and it burns you for 2 when they have more removal than you have instants.

[Titanium Dragon]

I had thought of the black one being

Taboo Bog (I like your name better though)
Enchantment Land
(Taboo Bog is not a spell)
Add B to your mana pool whenever a creature you control is put into your graveyard from play.

This is weaker than your version, and still seems like a combo engine. I don't really think you need to add more than one mana per creature because it makes it harder to hit 20 mana from just one of these. I'm worried about its potential brokeness with a combo like Project X's, but then again, Project X can give infinite life instead, so I'm not sure it really makes a difference.

And I agree with the issue of the blue one, it bothered me as well. However, the blue one is not strictly better than the green one because the green one gives it to you during your turn, while the blue one doesn't. I think Andrew's suggestion of adding mana when an opponent plays a spell might be a good one; what do you think?

As for the red one... two in play doesn't seem like an enormous problem, though I should probably make sure that it doesn't enable storm too much. But given a storm deck isn't going to be able to go off with two of these in play until turn 5 or so, requiring five lands in play, I'm not sure how much of a problem it is.

[SpencerForHire]

Whenever a creature you control is put into the graveyard from play, add to your mana pool.

All I can think of after reading this is Skullclamp.  Good game balance.

[andrewpate]

Well, yeah, but it's banned everywhere but Vintage.  As I mentioned earlier, the most severe case there is that Kobolds is finally good, but "Taboo Bog" would get hosed by Leyline, which is currently ubiquitous.  You really see it as a problem?