Trek looks weaker than Outpost overall, especially considering the interaction with workshops. Outpost is pretty good though so being weaker is ok, I think it's balanced. I don't think the "cannot be reduced in price" is necessary.
and you had 4 Highways in play. Does this now cost 
or still 
since prices cannot go below 
? The order you resolve them in gives you different results, so we need something that either clarifies or stops cost reduction. Stopping cost reduction is far fewer words.
I don't know how much you care since it's a removed card, but Artist is strictly better than Feast.
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Yeah, it needs to restrict itself to non-green. It is fairly trivial (4 Labs) to get to a hand of 9.
I like choices, as long as they don't take way too long.
Warlock(v7)
Here, both players make a choice. The attacked player decides which cards to reveal to avoid a Curse, while the attacker chooses whether they discard those cards or gain a Curse.
"Any number of cards" includes 0 cards.
General
Should this cost 6 or 7?
I think it'd be fine at 6.
I have a very similar fan card I use sometimes, but it costs 4 and has a drawback to make up for the cheap cost. It's strong but not super strong.
You need to use an Action on playing this card, so I think it's weaker, unless edge situations like Spoils.How about making it able to play Treasure? Then it combines a weaker King's Court and a weaker King's Cache.
And there should be a non-Duration clause.
The problem with playing Treasures is that it wouldn't require an Action to play a Treasure. So instead of it becoming a weaker King's Cache, it actually becomes stronger, because now you can double-play Spoils without moving them back to the Supply.
MulliganIf I've drawn 2 cards at start of turn with a Wharf (I didn't play it this turn), is it 7-1 for 6 cards to draw, or standard 5-card hand draw -1 for 4? 1 fewer card makes the former make more sense, but hand draw I only associate with end of turn.
You would draw for each card discarded (minus one.) So if you had a Wharf in play, you could draw up to 7, discard 7 with Mulligan, and draw 6.
With Treasure Chest, you can gain all Golds!
