This is something a friend and I put together for the MIT anime club after we discovered most people in the club really like Dominion. We tried to strike a good balance with card flavor, though sometimes we just had interesting ideas and then tried to fit them to something. The expansion has a bit of a theme going about the top card of your deck.
We actually printed out a set of cards and playtested them, so I think we struck a good balance with most of them. The goal was for this to be an expansion of Dominion, so the cards were made with the other expansions in mind. (Except for Hinterlands, which was not released when we made this)
EDIT: Card images have arrived. The cards are in black and white because we don't have access to a good color printing service. Also black and white is a lot cheaper.
http://imgur.com/IIQNA,NjBld,VHnGT#0AT Field$2 Action-Reaction-Duration
Now and at the start of your next turn: +1 Action
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As long as this is in play, if another player plays an Attack card, it doesn't affect you.
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When another player plays an Attack card, you may reveal this card from your hand. If you do, you are unaffected by that attack.
Comments: We wanted a card that blocked attacks really well, but otherwise did little for you. At first this had just +1 Action, but we changed it to its current form so that it complied with Duration rules and wasn't always a dead card with no attacks.
Dragonball$2 Action
Trash this card and as many copies of Dragonball as you like from your hand. If you trash at least 2 Dragonballs, +$7 +1 Buy. If you trash at least 7 Dragonballs, +$70 +7 Buys
Comments: We wanted a Treasure Map-style money accelerator that wasn't so swingy. The +$7 was so that it couldn't be used to buy a Province by itself, and then the name just kind of worked with that number. The trash 7 effect is largely there as a joke, but if you somehow manage to pull it off, you flat out win unless your opponent already has 6 Provinces, which seems appropriate.
Sailor Scouts$2 Action-Reaction
+3 Cards
Discard 2 cards
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When another player plays an attack card, you may set this aside with as many cards as you like from your hand. If you do, then at the start of your next turn, discard the set aside cards; +1 Card per card discarded.
Comments: The reaction effect was created first, and just seemed like a neat idea. It went through a few different action effects, but this one was neat in that it was very similar to the reaction effect.
Deity$3 Action
Trash this card. Duplicate the effect of an action card in the supply costing $6 or less.
Comments: This used to cost $2 and was limited to $5 actions. The problem was it was too often the obvious best pick at $2, and it was too easy to pick them up with extra Buys.
Ninja Village$3 Action
+2 Actions
You may discard the top card of your deck. Put the bottom card of your deck into your hand.
Comments: A village that draws from the bottom of your deck, why not. We had to be careful to make sure it wasn't strictly better than Village so it could still be $3, but the idea was always a village with a way to get around topdecked crap.
Shinigami$3 Action
+$2
For each opponent, name a card type (Action, Treasure, or Victory). Each opponent reveals the top card of his deck and discards it; if the card is of the named type, he gains a Curse.
Comments: We wanted a weak cursing attack, and came up with this. It plays a lot like Swindler.
SOS Brigade$3 Action
+1 Card
+$1
Shuffle your discard pile and turn it face down. Reveal the top card of your discard pile, the top card of your deck, and a card from your hand. Put one in your hand, one on top of your deck, and discard the other one.
Comments: A fun card effect, though having to shuffle your discard pile can get annoying. This ended up being better than I thought it would.
Time Machine$3 Action-Duration
You may choose an action card in your hand. Play it and set it aside. At the start of your next turn, play it again.
If you do not set aside a card, at the start of your next turn, put this card into your hand.
Comments: I'm kind of surprised this wasn't in Seaside. It was originally $4, by analogy to Throne Room, but it turned out to not be as good and plays more like Scheme, so we dropped the price.
Bounty Hunter$4 Action
+1 Card
+1 Buy
While this is in play, all cards are Treasures that can be played for $1 (in addition to their other types).
Comments: We wanted a card that let you play junk cards in your hand for coin. Then we realized that was essentially Vault/Secret Chamber. So we spiced it up with the type-changing effect. On its own, I think this card is properly priced at $4. But it has a lot of weird combos with other cards, and that makes me wonder if it should be $5.
Detective$4 Action
+$2
Each player (including you) reveals the top two cards of his deck. You choose one to put back and one to discard.
Comments: Simple deck inspection attack. Kind of vanilla, but we needed some simple cards.
Floating Continent$4 Action-Victory
Reveal your hand. +1 Card per Victory card revealed.
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2 VP
Comments: For a while, this cycled Victory cards instead. We changed it back because it just wasn't that good. Also, this was made before Crossroads existed, though we copied its wording for the final version.
Miko$4 Action
Trash up to 2 cards from your hand. For each differently named card trashed, if it is an...
Action card, +2 Actions
Treasure card, +$2
Victory card, +2 Cards
Each other player may trash a card from his hand.
Comments: Tribute meets Bishop, and a bit of a different take on trash for benefit. I've got an eye on this for possibly being too good. I'd rather not move it to $5, but we'll see how it plays out.
Pokemon Center$4 Action
Reveal your hand. Draw until you have 6 cards in your hand that are not Curse cards. Then trash all Curse cards in your hand.
If you did not trash any Curse cards, you may trash a card in your hand and then draw a card.
Comments: We wanted some Curse hate, and this seemed like a fun way to do it. The generic trashing effect was added so that it could still get good use on non-cursing boards, and ended up bumping the cost up to $4
Heart of the Cards$4 Action
+1 Card
+1 Action
Name a card. Reveal the top card of your deck. If it's the named card, put it into your hand. Repeat until you guess wrong.
Comments: Wishing Well++. Honestly, this was designed purely off flavor. But it works so well that way that I like it.
Hell Link$4 Action
+1 Action
Name an Action or Treasure card. Reveal cards from your deck until you reveal the named card. Play that card, then trash it. Discard the other revealed cards.
Comments: A tutoring card with a hefty drawback. A decent opener, where it plays like a more reliable Loan. It has nice lategame utility when you need to dig up that vital action or a Gold to buy the last Province.
Iron Town$4 Action
+2 Actions
Reveal cards from the top of your deck until you reveal an Action card. Put that card into your hand and discard the other cards.
Comments: I was always torn whether this was balanced at $4. The fact that it skips over treasures ends up being a lot more of a drawback than it seems, but digging for actions is quite powerful.
Death Note$4 Action-Attack
Choose one: Gain a Curse or trash a card from your hand costing 4 or more. If you do gain a Curse or trash a card, each other player discards 4 cards.
Comments: This card was hard to balance. It started as a $5 and the curses scaled with the number of opponents, but it turned out that was a lot worse than we thought. I think we've reached a good place with it, and flavor-wise it works out if all the numbers are 4.
Geass$5 Action-Attack
+1 Card
+1 Action
+1 Buy
Each opponent with at least 5 cards reveals his hand. You choose one card in each opponent's hand. He puts the chosen card on top of his deck.
Comments: This used to be $4 and the card was discarded. That turned out to be...somewhat unbalanced. Topdecking the card at least means you get that good card next turn, and if their hand is already awful, you can screw up their next turn a bit. Also fits better with the "top card of deck" theme we ended up with.
Student Council$5 Action
+3 Cards
+1 Buy
Comments: We wanted a few vanilla cards because we'd be teaching people to play with this set. This seemed like a reasonable combination. Of course, Margrave now makes this look pretty bland, but it's hard to spice it up while keeping it simple. And yes, the name is a reference to Council Room.
Prosecutor$5 Action-Attack
+2 Cards
+1 Buy
Each player reveals a Victory card from his hand and places it on his deck (or reveals a hand with no Victory cards). Each player that revealed a Victory card then gains a Curse, putting it in his hand.
Comments: We also wanted a stronger Cursing attack, and ended up coming up with this. It self combos quite well, since the victory card ends up in your hand next turn. Putting the Curse in your hand lessens its power.
Grand Line$5 Treasure-Attack
$2
If this is the first time you played a Grand Line this turn, each other player gains a copper.
Comments: We wanted a treasure attack, and this seemed like the logical way to do it.
Equivalent Exchange$5 Action
Trash up to 3 cards from your hand. Gain up to 3 cards with total cost in coins exactly equal to the total cost in coins of the trashed cards. (You may gain a different number of cards than you trashed.)
Comments: This would have been Forge if Forge didn't already exist. Originally it was Forge limited to 3 cards, but that was kind of boring (and surprisingly bad), so we gave the option of gaining multiple cards.
Spiral Energy$5 Action
When you play this, count your deck and discard pile.
+1 Card for every 4 cards total between them (rounded down).
Comments: A draw card that scales with the size of your deck. It works well enough, but I wonder if the numbers could use adjusting.
Mecha$6 Action
+2 Cards
+$2
Comments: This was originally $5. That was clearly wrong. It seems to be working at $6.
Host Club$6 Treasure-Victory
$?
When you play this, it's worth $1 per Host Club you have in play (counting this).
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1VP
Worth an additional 1VP for every 2 Host Clubs in your deck (rounded down).
Comments: We knew immediately we wanted a male version of Harem for Host Club. It scales with the number you have, which seems logical for a harem.
Card RulesTime Machine and self-trashers--If you Time Machine a self-trasher, it loses track of the card and can't play it again the next turn. Time Machine may return to your hand in this case, as no card was set aside.
Time Machine on Time Machine--Suppose you use Time Machine to play Time Machine, and then don't set aside a card with the second one. At the start of your next turn, you may either play it again or return it to your hand, but not both.
Trashing Duration cards--If a Duration card is trashed after you play it (either through Deity or Hell Link), you still get its "at the start of the next turn" effect. You don't get its in-play effect.
Bounty Hunter--All cards have type Treasure in addition to their normal types while this is in play. Actions played as treasures will not have their action effects, but will have their in-play effects. Cards that are already treasures can be played for their normal effect or for $1, your choice.
Equivalent Exchange--You may choose to trash no cards. In that case, you may gain up to 3 cards with total cost 0. Similarly, if you trash cards with total cost 0, you may choose to gain no cards. And yes, you may choose to trash no cards and gain no cards.
These are the ones that are most obvious. If you can think of any other potentially weird interactions, tell me.
