We have a Watch List for a reason: some cards just turn out ridiculously broken. Unlike WotC, we don't have time to playtest sets for a year, and even they miss a few things. And while we at HGML cultivate a more powerful environment, certain cards become just too abusive. Those that seem dangerous are put on the Watch List, and if they remain unanswered, they are errataed. In this article, I'm going to explain our reasoning behind each card's erratum.
Mason's GuildThis is one of several cases where a card wasn't very good, so we made it better, and overcompensated. A defensive powerhouse that was also capable of shutting down your opponent's mana production, this thing came out so early and started trading Iouns for lands so fast that the opponent couldn't do much about it, and any creatures sent against it ran into rather large walls. At 2RR, this card is still very good, but opponents at least have a chance to get rolling before it comes out.
TechnopotenceWhat did we expect making a blue Necropotence? Why the hell would this even sound like a good idea? The fact that HGML is defined by cheap, 0 and 1 cost artifacts didn't bother us at the time, but a blue deck drawing 8 cards a turn for no real cost caught our attention. With all the Iouns, this may still be abusable, but a significant portion of your deck would have to be artifacts, which still isn't that hard.
Latent PyromancerThis is still an efficient use of mana, and red needs all the help it can get, but this thing killed stuff coming in, going out, then came back and killed some more. That sort of card advantage was really rather ridiculous.
Ioun Stone, EtherOkay, this one is entirely our fault. We knew coming into play tapped wouldn't be enough to offset a free source of any color, and so thought returning it to your hand would slow you up a bit. But we were stupid and forgot that it costs 0, so you can replay it right after tapping it, effectively giving any deck that wants it a free source of any color, if they're just willing to wait a turn for it. This enabled to stable a mana base for multicolored decks, as well as just speeding things up too much. Now, you can only use every other turn at best, and have to keep in mind that it won't be available the next turn whenever you want to tap it.
Ioun ValleyI don't know what we were thinking here. I saw this in many monocolor decks, that would tap it and take manaburn just for the card. I even thought this was nuts when it came out, and if I think something is overpowered, well it has to be true.
Well, I hope this makes sense. Sorry for the inconvenience, but in order to maintain a fun environment, we need push the bullies down a few notches.