Half a year ago on BD I tried to start a discussion on Dwarven Miner in Keeper, but since BD was already in the state of dying I did not get the response that I got for my Undiscovered Paradise post the year before (now it seems, that UP is a standard choice for Keeper). So... Let me try to start the discussion again (and maybe 1 year from now Dwarven Miner will be a standard choice

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Just for your convenience, in case you do not remember:
Dwarven Miner; cc 1R; P:1 T:2; ability: 2R, tap: destroy target non-basic land
Why should you play Dwarven Miner in Keeper?
1. It fits the silver bullet theme
The story of Keeper is a story of silver bullets combined with Tutors and draw-cards to fetch them, counterspells to protect them and defensive spells to survive long enough to actually cast them. Usually people play The Abyss, a silver bullet against most creatures (especially nasty black ones), Gorilla Shaman, a silver bullet against cheap non-creature artifacts (most notably Moxen which of course is the reason for its nickname, Mox-Monkey), Mindtwist, a silver bullet against the opposing hand (i.e. against any deck that cannot counter but is still slow - e.g. Parfait or Sligh with 8 blasts). So in summary, you have silver bullets against the hand, against non-artifact targetable creatures and non-creature artifacts. That leaves you vulnerable to
enchantments
artifact-creatures
non-targetable creatures
sorceries/instants
lands
Hopefully, your defensive non-silver bullets take care of them (Counterspells, D-Blow, Edict, Strip/Waste). However, in case there were many enchantments around you would be afraid of, surely you would consider a silver-bullet, right? Similarly, in case there were many artifact or non-targetable creatures, again you would consider a silver-bullet. In fact, against certain types of sorceries/instants many Keeper player actually do have some silver bullets, at least in the SB (e.g. COP: Red or Compost).
However, few people seem to consider silver bullets against (non-basic) lands nowadays, which is even more surprising considering the fact that originally (some) Keeper-decks played Blood Moon. I can perfectly understand everybody who is reluctant to play Keeper with Blood Moon (ask Milton if you want to go THAT route). But against non-basic lands there is a perfect alternative available: Dwarven Miner.
2. An analysis of the various matchups
Keeper:
Against Keeper it is simply devastating. The worst case scenario (for you) is that it is a 1-for-1 trade. But at the moment it starts eating lands, it is already great. After a few turns all you have to do is wait patiently for his attempt to cast a Balance and counter it (if you are REALLY evil and you can afford it counter with a hard cast FoW just to show him his limited resources). Later you can just attack (you need not even bother with Morphling).
Combo:
Your main concern is, of course, to prevent the combo deck from going off. Dwarven miner does not help much here, but it helps more than e.g. Morphling does (or Tome, or Braingeysir, or Regrowth or Masticore or ... - DM is not really comparable to any of these cards, but since you will probably want to take out one of these for testing DM I decided to list them). Combined with Mox Monkey you can mana-screw him completely, provided you were able to survive the first 4 turns with counter-magic and/or luck.
other multi-coloured decks or most Workshop variants:
Clearly, DM is great against any of these decks.
Forbiddian:
If he is playing a Legendesque (i.e. only basic lands) variant DM does not help very much. But these decks are not a big thread anymore after the FoF-restriction (still very good, but not broken). Against ordinary Forbiddian decks DM can occasionally destroy a Factory, a LoA, sometimes even a Strip/Waste or a Thawing Glacier (or the evil DustBowl!). It can also block Ophidian repeatedly, which is just an added value. And if everything else fails he is a, um, 20-turn clock. Often you may want to side him out in these matches, but against my local Forbiddian-decks I usually leave him in the deck, since they play about 12 non-basic lands all of which are evil. So despite of the fact that DM might not be great in these matches it is still ok. Just beware of the random Control-Magic! (As if Forbiddian is ever going to side THAT card against Keeper...)
Sligh:
Again, in Legendesque variants DM is just a Bolt-absorber or it might even be a blocker (often it buys you 1 turn, which is ok). Versus Factory/Barbarian Ring variants occasionally you will be able to eat some land. Usually you will side it out, but it is ok since it is cheap enough to buy you an extra turn in the early game.
NetherVoid/Pox/Sui:
The blocking and attacking issue is of minor importance here (ok, sometimes you are desperate and you block a Negator and 1 turn later you draw the card which wins you the game, but most of the time Miner is not very good in terms of Power/Toughness). If the deck splashes e.g. White (as some Pox decks do) Miner is already ok/good. In variants with Factories and/or Ports it is also ok. But you definitely want to side it out in games 2/3 (after all, your plan A is to drop The Abyss ASAP and Miner and The Abyss do not mix well).
Stompy:
A dead card, in various senses. Still, it might buy you one turn. But side it out in game 2/3.
3. A summary of the above analysis
If the decks to beat are Keeper, Combo, multi-coloured decks, Forbiddian with Factories, two-coloured variants and Sligh, then DM is very good and should be played maindeck (you can still side it out in games 2/3 against Sligh and Forbiddian, if you wish). If, however, most of the dangerous decks you encounter are mono-black or Stompy, do not bother with Dwarven Miner.
4. The mana issue
You should consider DM seriously if and only if you play at least 3 Vulcanics+1 UP or, alternatively, 4 Vulcanics (I prefer 4 Vulcanics+1UP, but 3 is still ok) on top of the 4 COBs and the Ruby. After all, you are vulnerable to Wastelands and it is somewhat embarassing to cast a Miner and not be able to use it due to lack of R. Since most Keeper player have to beat other Control decks (and thus play a couple of REBs) they play 3-4 Vulcanics anyway, so this is not a big deal.
5. Tricks with DM
There are not many stack-tricks you can perform. Let me just point out that often it is advisable to wait and use DM EOT. Sometimes, you might even hold back the attack (despite the absence of non-basics) in order to be able to destroy an eventual land during your opponents turn (can be of importance in some games against control). When DM is happy, you should consider to start attacking. Note that often you can play him first turn (which is why he is so devastating against Keeper). Note also, that you can Tutor for him (not that you did not know, but since this card can win you the game I thought I should point this out). Er, yes. You can also block and attack, and should you block and DM is about to die it is always nice to eat a land as last supper. And (not that this was an important point, but still...) if your opponent uses an Edict, well, that is one Edict less against your Morphlings...
6. Synergies and lack of them
DM works very well with Mox Monkey and Timetwister in the same deck. In fact, Timetwister helps you a lot against mono-B, so even if some of the dangerous decks you encounter are mono-B do not be afraid of using DM if you also play Timetwister (as I would reccomend). It works especially well with enough red mana (see 4.). It does still work fine with Moat (for those rare decks which still play them MD - you just cannot attack anymore), although if your metagame is such that Moat is a good idea, DM most likely is not. It does not work fine with The Abyss. But usually this is not a big deal. And finally, sometimes you have to be careful if you plan to play Balance soon. Playing a DM thoughtlessly might cost you a game in such occasions (e.g. when you play a Miner, he has a flyer, keeps attacking and your only defense is Balance). Otherwise, there are no relevant non-trivial interaction with the rest of the deck (yes, you can YawgWill it, but I do not have to explain that to you, right?).
7. Counter strategies and how to prevent them
The worst card is Balance. Not only does it get rid of DM, it also restores land parity. Fortunately, casting a Balance (and being able to protect it with enough counterspells) is not an easy task without lands (or with only few of them). Still, beware of Black Lotus/Balance plays (i.e. keep your Counterspells, do not tap out during your mainphase etc. - the most dangerous thing is if you start to play "stylish" - keep calm, eat his lands and finally start to attack).
Edict or Fire&Ice also kill DM, but it is a 1-for-1 trade. StoP is also a 1-for-1 trade, but it is usually a dead card against you, so being StoPed is not a good trade for a DM - but there is nothing you can do about it (except countering of course). BEB is a rarely played card against Keeper, but it does its job. Be sure to laugh at him, when you play your YaygWill protected by a FoW and he shows you a BEB (the point I want to make is that BEB, while great against Miner, Mox Monkey and REBs is completely dead against the other 55 cards in your deck). The Abyss is bad luck. But you can stil use him once, if I understand the ruling correctly. Not great, but not bad either (much like a Wasteland). And NOBODY is going to keep The Abyss against Keeper, and if they do, well, good luck to them! Post SBing, the best cards he can have against DM in the mirror match are Edict, F&I and Balance, two of which are also good against Morphling and three of which are also good against Mox Monkey - so your other threads are more likely to survive. Other cards are minor issues - e.g. Powder Keg kills it, but it takes 2 turns and this way it doesn't kill your Moxen, your Mox Monkey or your Morphling. Anyway, in almost all cases we are talking about 1-for-1 trades, which are ok.
The main point about 1 DM (2 post SBing) is that either way they have a problem: if they do not play any defensive against it, they have to rely on counterspells. If they do play defensive cards, they might not even encounter your DM and run into a Mindtwist, a YawgWill etc. Even if you do play DM (as I would highly recommend), do not forget that you have still 59 other cards in the deck.
8. A sample decklist
Because I do not want to confuse the issue of this thread with several other Keeper threads, I do not present a SB, neither do I include Cunning Wishes, Impulses or Holistic Wisdom. This decklist is about 3 months old and I have used it in several T1 tourneys.
Keeper with Dwarven Miner (60 cards):
mana: (28)
4 COB
4 Underground
4 Vulcanic
2 Tundra --> it is ok for me, but you might want to play 3; take out 1 Waste or 1 Vulcanic instead
1 UP
4 Wasteland
1 Strip
1 LoA
7 SoLoMoxen
blue (20):
4 Mana Drain
4 FoW
1 Counterspell
1 Mis-D
2 Morphling
1 Ancestral
1 Walk
1 FoF
1 Stroke
1 Mystical
1 Merchant
1 Timetwister --> great synergy with Mox Monkey and Dwarven Miner!
1 F&I
black (6):
1 YawgWill
1 Mindtwist
1 Demonic
1 Vampiric
1 Diabolic Edict
1 The Abyss
red (2):
1 Mox Monkey
1 DWARVEN MINER
white (2):
1 Balance
1 D-Blow
green (1):
1 Sylvan Library
non-mana artifact (1):
1 ZOrb
9. I want to test Dwarven Miner, but what should I take out?
In no particular order (since I do not know your decklist): Regrowth, Braingeysir, Tome, Masticore, 2nd Mox Monkey, 2nd StoP, 2nd Edict, 2nd Merchant Scroll, Vindicate, 3rd Morphling, ...
10. Have fun and let me know how Dwarven Miner works for you!