I don't want to go
too deep into artifact sacrifice as a theme, but I do feel like their should be slightly more cards that can create value from the wellsprings. The stars and spheres are positioned pretty well, and generally you aren't going to want to be sacrificing those to draw a card (I don't think). Everytime they get played they tend to be used very quickly to either color fix, or smooth out ones draws.
I'm more interested in adding a little more play to ichor and mycosynth wellspring. Pre-patch, I have
etherum astrolabe,
perilous research,
ghostly flicker, piston sledge, and
throne of geth to interact with them. Astrolabe kind of dosen't count, because its a nudge card, and
throne of geth meshes poorly as the only deck that would want that affect is a heroic deck, which dosen't want a do-nothing artifact. Because I cut two
ghostly flickers, I have been running really 3 cards total in the cube that can get value from the wellsprings. Those cuts, throne underperforming, and astrolabe being multi-color, are why I think I a running a little light on the effect.
Trading post,
astrolabe,
perilous research,
phyrexia's core and
ghostly flicker are a nice lineup for control decks, but I am still stuck with just
piston sledge for aggro (though piston sledge has been great). I'm a little nervous about cards like shrapnal blast and atog, because they do nothing without artifacts. I hadn't considered
goblin welder, but it looks really good. It could be run in more aggressive decks, or more midrange R/W decks looking to abuse
auriok salvagers.
Orcish mechanics is interesting as well, and might
just be good enough to squeeze in.
I have a pretty casual playgroup, so you could give them the best aggro cards in the world, and they will still try to find a way to play midrange and control.
Magmaw is something I should keep on the radar though, especially since it works so well with aggressive token strategies.
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The smiths vary a lot in value.
Embersmith has been very good,
myrsmith has been a solid roleplayer,
lifesmith has been pretty lackluster. Riddlesmith and painsmith haven't come up yet, the former not being very surprising though. There is still that stereotype that blue is a poor aggressive color, and when my players see a 2 power blue creature for 2, they tend to stray away. It will take a little while for that to change. Not sure whats up with painsmith as he has been in the draft.
The Zendikar ETBT lands have been
really cool. Getting 2-3 uses out of something like
Sejiri steppe is awesome. Last week I was keeping myself alive with my army of plant tokens.
I might end up making the same swap that you are with
myr retriever.