Okay, so I've noticed that frequently when a newly suggested card is exploitable it's because the same few cards weren't taken into account.
Note that I'm not saying these are necessarily OP (there's another thread for that discussion), I'm saying these all have potential to break the game if combined with cards that didn't take them into account.
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Fractal- I'm sure everyone has seen at least 1 or 2 creatures in the card ideas section that got shot down because (card)+fractal=OMGWTFBBQ!!!
Rustler- Rustler can make lots of
quanta from
and at a 2:1 exchange ratio. This is important on 2 accounts: 1) you can get lots of
really easy, and 2) if you aren't careful with card design you can accidentally make infinite quanta loops, which are bad.
Supernova/quantum tower- It's really easy to get ridiculous amounts of quanta in just a few turns if you don't care what type. Affects any "other" cost card. Kael is currently looking for a good way around this. The most popular suggestion seems to be to make some cards that cost "other" take all their quanta from the same type.
Cremation- Has a lot of the same uses as supernova, but gives you a whopping 9
right away. Makes it really easy to get
in a hurry.
Mindgate- Someone found a game-breaking combination with this card really quickly after it was introduced (it has been corrected since), and there's a good chance more will come up later. It's a new card, so a lot of it's secrets are TBA.
Farm decks- Not every deck in the t50 is going to be intended to be hard to beat. Frequently people will design decks specifically so other players can get rares by beating their t50 deck. The mindgate gamebreaker was due to the potential for infinite hp victories resulting from a specific type of farm deck.
Dive- Creatures with the ability to double their attack can cause problems with a lot of different creature buffs.
Quintessence- Any creature can be made immune to CC
Rain of Fire- Massive CC, one of several ways to make lots of creatures die quickly.
Nightfall- Darkness and death creatures are relatively easy to mass buff.
As a more general note, not all quanta types are equal.
are generally easier to get in large amounts, whereas
are generally a little harder to rush.
is sort of neutral; no
cards particularly increase quanta production, but
can draw very fast and get more pillars in play faster.
and
can both dramatically increase the rate of production for other quanta types.
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Let me know if you think anything else should go on the list.