When I started playing T1 competatively... it was right around mirodin - and Worker/Staff was my deck of choice (that and T1 affinity). For years that deck has been shelved away in some folder deep in the bowels of my MWS folder. I have recently re-considered it when I read the following card on the Spoiler for the new set:
Rings of the Brighthearth 
Artifact
Whenever you play an activated ability, if it isn't a mana ability, you may pay 
. If you do, you may copy that ability. You may choose new targets for that copy.
How does this effect Worker/staff? Well in a few ways - firstly, it lets you combo out with only 2 artifacts in hand (with a kick-off 1 mana). How?
-Tap worker for
+ the
extra mana.
-Activate staff's 3rd ability to untap woker.
-Rings trigger, use the other
in your pool to copy the untap targeting the Metal worker again.
-Let the copy resolve, and then tap worker in response to the original untap your pool is now
-Worker untaps again and now spend
to untap staff, and you are where you started with +2 mana. (so tap worker to go to
, then you can cycle this to have 6 mana yield 8 mana... every itteration goes up 2 mana).
How else can this card go infite?
>> Basault Monolith +
in the pool
-Tap monolith for
plus the
=
-activate the untap, and copy it (5 mana).
-now you have 2 untaps on the stack, so tap monolith twice for
.
-with your 6 mana you can untap it twice for 5. So 5 mana => 6 mana infinitely.
* note that grim monolith doesn't work here. Because the 4+2=6 ...
>> Timevault + (an untap) + 2 mana.
-In the untap step, skip a turn and untap vault.
-At any point this turn, tap vault and copy for 2 mana.
-- So now the game tells you "take an extra turn, take an extra turn, but Skip your next turn." So you start to your first extra turn, but that turn gets skipped - but fortunetly you then go to your second extra turn. In this extra turn again untap vault and repeat for infinite turns.
*note that you can not skip your turn any time you want anymore. So most likely you'll have to pass the turn to go infinite next turn after you play vault. Unless you have something like Voltaic Key.
>> Deserted Temple + 4 mana land (tolarian)= infinite mana.
-Tap tolarian for 4 mana
-Activate Deserted temple targeting Tolarian. Copy the ability for 2 mana, and target Deserted temple (total 3 mana).
-Both lands untap and you have 1 in the pool. repeat for infinite.
>> Worker (with 2 artifacts in hand) + Key.
- Tap worker for
mana.
- Activate Key, and copy it targeting Worker and Key leaving
in the pool.
- Repeat
>> Voltaic Key + Candelabra + 2 city of Traitors (or Tolarian @ 2)
- Play City of Traitors from hand, with one in play. With the Frist city's sac triger on the stack...
- Tap both cities for
- Tap Candelabra: X=2 + copy =
in pool ; untap both cities twice. putting
in the pool.
- Activate Key and copy it targeting candelabra and key, Leaving
in the pool.
- You can continue this arbitrarily high - but remember that the Sac City of Traitors is still on the stack. Don't worry about floating ludicris amounts of mana though. So float 1,000,000 mana then sac your city. If they counter your staff from hand you can use the same loop with X on candelabra = 1 to "unload" your mana.
So this Combo is probably better than deserted temple, even though it requires more peices. It's better because each peice is useful on it's own... where deserted temple is fairly terrible unless you have a Tolarian in play. The same could probably be said about Candelabra and Key, but at least those cards are artifacts for metalworker to work with. Also Key alows the Timevault combo to go off as soon as vault resolves.
Also this combo can mini-work with something like Ancient Tomb. It becomes rather channel-esq though because you end up paying through the nose for each Tomb untap. But it may give you the mana needed to ramp up to something bigger.
List Proposal:
lands/free mana
4 Workshops
4 City of Traitors
4 Anceint Tombs
1 Tolarian Acad
2 Urbrog's Tomb
1 Vault of Wispers / Academy Ruins
5 Mox
1 Lotus
1 Mana Crypt
-23--
Non-free Mana
4 Metal Workers
3 Candelabra
3 Basalt Monolith
1 Sol Ring
-11:34--
4 Staff of Domination
2 Timevault
1 Goblin Cannon
1 Platinum Angel
-8:42--
4 Rings of the Brighthearth
3 Voltaic Key
3 DT, Vamp, Will
3 Planar Portal
1 Memory Jar
-14:56--
3 Sphere of Resisance / Defense Grid
1 Tinisphere
-7:60--
Advantages:
1) It's a combo deck that (outside of will) doesn't care about the GY at all.
2) It is not as much of a lynch-pin deck as MUD worker/staff was. It can combo out with many combinations of cards. It doesn't need metal worker to get infinite mana -and- off infinite mana you can win with: Goblin Cannon, Staff, Jar, or Planar Portal(for staff). 3) It has some really simple and powerful "god" hands. Outside of Shop+Metalworker+Staff hands, you have stuff like:
Tomb/city
Shop -or- Sol ring + any land/mox -or- Mox x3 -or- Mox+crypt -or- Tolarian
Timevault
Rings
+ any 1-3 cards (depending on mana combo)
That's a turn 2 infinite turns! If you add Key+lotus/crypt to that it's turn ONE infinite turns. Add trinisphere and its turn 3 infinite turns - but where they can't play or counter antything.
Note on Academy Ruins. This can be nice for not decking yourself. Let's say Plats get's Swords. You can use Acad to recur your Goblin Cannon. Let's say that's RFGed as well - but you have inifite life, and Vault for infinite turns. Even if your oppoent has three 4/4 blockers. You can still win with Acad, even if you have 0 cards in your deck.
- For 4 turns: Upkeep return A metal worker from GY to deck. Draw him and play him.
- Turn 5: durring your upkeep pop lotus to return lotus. Draw it for turn and play it. Attack with 4 Metal workers, and 3 will die and 1 will connect for 1 damage.
- Repeat infinitely.
