So here's my entry from the recently ended challenge (#47):
And the feedback from the judge (Aquila):
Infusion/Cauldron (scolapasta)
Event, P +1 Buy, trash a card you have in play for + $1 per $2 it costs, if it costs $4 or more take Cauldron, then play any number of Treasures from your hand.
Artifact, Potions have "Choose one: +P; or + $3".
The Potion cost of the Event is a great idea in this contest, you play the Potion repeatedly to compete for the Artifact. But how many Potions does one get so that they should turn into Gold for deck payload? And seeing that this won't be a permanent feature, why not just get Golds? The half-Salvager bit would work for removing the Potion you used to pay for this, if the Cauldron didn't imply you should try to keep it; otherwise it has a few niche uses.
Overall: I feel Cauldron should do something else, but Infusion is good.
It's interesting, because I actually came up with Cauldron first, and Infusion was an attempt to find its companion Event.
• "how many Potions does one get so that they should turn into Gold for deck payload?"
Some of my thinking here was that you would keep getting potions in order to feed this engine payload. If you had 3 potions you could buy a Province (whether you had the Cauldron or not, though if you didn't you may have to trash one of the Potions to get it and find some space to replace it - though instead of the Province you could buy two Potions)
• "And seeing that this won't be a permanent feature..."
The purpose of the "Play any number of Treasures from your hand phrase" was so you could always get the benefit if the Cauldron at least on the turn you took it.
• "...why not just get Golds?"
Well, $4 Potion / Golds are cheaper than $6 Golds
• "...removing the Potion you used to pay for this, if the Cauldron didn't imply you should try to keep it" - I saw this as part of the challenge, that you have to keep burning through a Potions to overload your Potions, so you'd have to make decide whether you trash that Potion or some other $4 card.
So, what do others think?
A couple of ideas I had to change to try and make this better, would be to change the requirement to take the Cauldron from "If it costs $4" to something else. How about "If it's a Treasure"? then you could trash coppers early to get the cauldron, but later you'd have to sacrifice one of your Potions...
Another change could be to make the Potions better than Gold, i.e. +$4.
Lastly, here is the other alternative (rather than the 1/2 Salvager) I had earlier considered and already mentioned:
i.e the Villa variant
This might also need the change to the "if it costs $4" change. And even if it doesn't work here, I'll probably work with it as a different event for some future challenge.
Note: In order to post a little more here, I think my new idea is to try to post each challenges' cards)) each week after they're judged. Eventually I'll go back and include past challenges. But I like the idea of getting them out here while they're still fresh and often while we're still waiting for the next challenge.