Barron from my testing I have found the mancer to be a nice card to have. As it is a great creature removal spell. Though darkblast is nice to have too with the black splash. Me I have personally been testing with both the mancer and the darkblast. I have replaced the 3x bolt's in the deck with blast. The bolt is a nice card to have. But when I think about it. I find I use the bolt as a removal spell more then anything. And that I am never really killing anything with it that a darkblast can not kill too. Plus as other's have pointed out the blast help's let you keep a grunt out longer which is always a good thing.

As for the mana base. I have found that with the 3rd color splash that I want all 4x bloodedstained mire's in the deck now. And that I want wooeded foothills as the other fetch lands. The reason is that a foothill can go and get a badland's or a plateau and the lone mountain if needs be. Where as the windswept heath can only go and get a plateau. I know origanly the reason that the deck played odd number on the fetch lands was to help the deck out a little bit better agains thing's like pithing needle. But now with a 3rd color in the deck. I think you really need to worry more about making your mana base better and not try to play around something like pithing needle. I mean if you really think about it how many times is your oppoent really going to drop a needle naming a fetch land. When there are thing's like wasteland, mancer, kami's, crypt, factory and genju for them to name first. I am not saying that you are wrong though. I am just giveing my option on the mana base.

Well I hope that helps some.

Now I do not play MDG but I have played against it more then once with my deck. And there has never been a single time when they went the darksteel plan. The reason is that my deck has to much main deck darksteel hate for them to chance it. So they have had to go for the tendril's kill every time.

And now day's as I pointed out to someone just friday. With Hide/Seek seeing more and more play (at least in my area). Just playing the the one tendrils SB and the tinker main seems to be a problem. The reason is that if the play resolves a Hide/Seek they may just have won the game. Take my deck (which has just started to run the Hide/Seek) as an example. Now I know that I do not need to worry about the darksteel to much as I have a good number of answer's to him in the main. So I know that the tendril's kill is my only real worry. So if I can resolve a Hide/Seek early then all I have to do is go and get his burning wish. And then from there is is almost GG.

Now I know this is not as easy to do as it sounds with all the FOW and Misdirestions (though most I builds I has seen only play 1-2 misdirestions) and other counterspells. But the ability is still there and is something you have to worry about.

So with this in mind would it not be maybe a good idea for this deck to start to run 1x tendrils main deck too. And also leave the one in the SB. This way you can go and get the one main deck too if you need to.

Like I said though I do not really play the deck. This is just my thoughts on it as someone who plays against it. And with that prospective what I see some of the weaknesses of the deck to be. But I could be totally wrong.

Here is the list I have been trying out with the black splash.

Creatures
4x Goblin Welder
3x Grim Lavamancer
3x Gorilla Shaman
3x Hearth Kami
3x Jotun Grunt

Spells
4x Magma Jet
4x Swords to Plowshares
4x Lightning Bolt
3x Hide/Seek
2x Crucible of Worlds
2x Null Rod
1x Vampiric Tutor
1x Demonic Tutor

Mana
4x Mishra's Factory
4x Plateau
4x Wasteland
4x Bloodstained Mire
2x Wooded Foothills
1x Badlands
1x Scrubland
1x Mox Ruby
1x Mox Pearl
1x Stripmine

As for the SB I am consinatly changing that up to match what looks like is going to be run at the tournement.

Now as for the deck itself. I know it may look a little odd but I am not playing in a powerful meta. So while I do see a few of the tier 1 decks out there I also see a few of the homemade kind of deck's too. That is the reason I run things like the 2x crusibal's and the Null Rod's as they can help out a good bit.

I also am only runing 3x Maindeck Hide/Seek. The biggest reason is that I could not figure out what I wanted to cut to make room for the 4th. I am thinking that maybe I should cut a bolt to make room for it. But I kind of like the bolt as it has won me more then a few games by leting me actually burn my oppoent for that last 3 point of life. But maybe the Hide/Seek is just a better card only testing will tell me that.

Though I have a question with the black splash does this mean that Phyrexian Negator is a viable SB option now. I mean hands down the grunt is just a better beater for this deck. But against a creatureless or creature light deck this seem like it would be good. I mean think about it now you not only have a 4/4 beater for two mana but now you also have a 5/5 trampler for three mana for them to worry about too. This means that they are forced to be abal to deal with all of them in the first few turn they come out or it is game over. The draw back to the negator is that if they can start hiting it for damage then they can totaly wipe you out. I guest the question is are there that mana decks out there that do not run that mana creature and do not have a way to deal with this. And if so is that match up bad enough to even warrent taking up SB slots for the Negators. What do you all think about the Negator in the SB idea. Like, Dislike, and why.

I was wondering if maybe this list need the lone Lions eye diamond in it too. This is another lotus for this deck. And also maybe the lone Pyrite spellbomb.

This mayb let the deck combo out a little faster. As in this case all you need is a salvager and either a Lotuc or LED and the pyrite spellbomb to win then and there. This may help make up for the lack of control elements in the deck. The nice thing about this too is that a trinket mage can tutor up any of the arfitact's needed for the combo.

Just a few ideas for you to think about.

Wow you are only running 2x factorys. How is this working out for you. I too love the way this deck works and am also in a very mixed meta. Some times I will see actual power type 1 decks and other time's casual type 1 decks. And I have found that

3x-4x grunt's
4x Factory's
3x-4-x Hearth Kami/Kataki

Is a must. At least in my testing of the deck. The reason is that this are you beat sticks. Like you said the decks run's a lot of 1/1's. But almost all those are needed as utility creatures. So all you 2 power guys and grunt are what really wins you the game. And factory is just an amazing card to run in this deck.

As for the grunt lavemancer conflict. I have found that this is really not that big of a conflict. As I use the mancer manly for removal not as a burn guy. Now if my oppoent's life total get's down low enough then yeah I will start useing the mancer to shock him to death with it. But for the most part I am not useing the mancer to remove cards for my libary. And I have also found that if the grunt can stick around for 2-3 turns (as you should really only play him if you know you can get through with him) then that is all that is really needed for the game.

Though I am still new to the deck and still testing it out and also my build is a little odd. So I could be wrong on some of this. It is just this is what I have found from my testing.