Let's see what you all came up with!
NoMoreFun: Wealth Hoarders/Incoming Raid
Comparison obviously goes to Treasure Trove for the treasure dump onto your deck, and I think the constant Corsair attack pairs well with this. Either you're going all in on this for your strat or you're going treasureless to avoid the Raid. Solid card, seems a bit like too much of an automatic opener though especially if you've got something like Spice Merchant on the board but that probably wouldn't play out on real boards.
MrHiTech: Insane Witch/Fata Morgana
Fixed Young Witch, I don't know how else to put it. Cost increase probably isn't going to matter much but that's not why you're buying it anyway. Feels about equal to Old Witch in terms of power level and I think that's a good spot to be for a Witch variant.
fika monster: Economic Boom/Recession
Spike of resources, boom it all collapses, and then you've gotta build them up again. Good theming and promotes draw-to-X which is always a nice quality to have in a card. Not my favorite because it feels like you're just piling on resources onto this for the sake of it but it works well so that's minor. Opponents getting a VP chip feels a bit unnecessary though.
IlStrawberrySeed: [unnamed card]/[unnamed premonition]
Good vanilla-ish merging of the two expansions this comes from. Don't know much about how this would work in practice with Laws and Monsters and stuff so I'm just gonna leave it at that.
Uzdu: Fence/Earthquake
For a card similar to Altar, $3 feels a bit cheap. Sure, there's a narrow window where you actually get to get $5s and higher with this, but you do get to get $5s and higher with this. Probably needs a price adjustment to about $4, but other than that no complaints.
emtzalex: Floating City/Crashdown
You'd think this would feel similar to Fence but it doesn't really. Both have the trash to gain from trash aspect but this feels like Tournament where you're building your deck around trying to get these, but unlike Tournament you're not just winning the game when you get a Province (or in this case Floating City) early. Some boards this might not have an impact, but the ones it does it goes hard. You'd expect it to just be a won game if your opponent gets one and you don't, but they have to get like seven Golds in their deck and then trash them with this to pile out the Floating Cities and by then you'll probably be able to snag enough Provinces and stuff to win anyways. Overall, solid card, game warping but in a way that seems more fun than Page/Peasant do.
X-tra: Crow/Swarm
Peddler Curser. Seems nuts (well, is nuts) so everyone gets a perma-Moat for seven turns, but I don't think that's enough. Antisynergizes against itself because cantrips really don't like Curses (as opposed to stuff like Sea Witch which self-counters) so it's probably more balanced than I think it is, but man does this feel insane. Premonition's implemented well though, always sucks to lose a $5 opening to a Militia or something.
Honorable Mentions: Fence, Insane Witch
Runner-Up: Wealth Hoarders/Incoming Raid
Winner: Floating City/Crashdown
Thank you to all who participated!