Browsing through the topiques I realized that the concept of something is overpowered or underpowered is a mixture. Many times players disagree because they're talking about different things.
In my opinion, the cathegories of over/underpowered cards should be defined first - then the possible buffs/nerfs are to be discussed.
Sorry if such a topique existed before.
The following examples reflects
my opinion, so, if I say a certain card is overpowered it does not essentially mean that it is.
1. Overpowered card - the card itself is too strong compared to the costs of it and, compared to the possible ways to counter it.
Example:
Rage Potion/Elixir - for a reatively small cost it gives great versatility; kills any creature with 5 (6) HP or less
plus it can boost any own creature with more HP.
Possible solution: raise the cost or lower the effect.
2. Context-overpowered card - in this case the card is not overpowered, however, the (most probable) usage of it fits in already powerful decks with no additional "cost", or, generates a "cheap synergy" situation.
Example:
Shard of Wisdom - in theory, the card is very situational, can be used only on immaterial creatures. However, in most cases this Shard shows up in Mono-Ether decks. Take a look at these decks
without the Shard. Mono-Ether can be made entire of immaterial creatures - besides shield effects, no creature control works against them. Phase Dragons are hard-hitter too, they can provide a good damage output. Incoming damage can be stopped by Dimension/Phase Shields, annoying creature skills can be ripped off by the Lobotomizer/Electrocutor. Also, Psion ignores Shields, and can be immaterialized too. Lightnings can kill problematic creatures. Playing against Mono-Ether one should remove the Shield chain, get a good defense, outdo the damage etc. In short: with the exception of permanent protection/control Mono-Ether can do well against most decks. In my opinion, the main disadvantage of the deck that is very expensive. With the Shard added, Mono-Ether can ignore Shields by creatures which are still untargettable. The hard counter shields (Mirror/Jade) are too situational. So, the problem is not the Shard
itself, it's the deck fitted in. Also, the Shard is cheap, playing it requires technically no real cost compared to the other cards in the deck.
Example#2:
Ghost of the Past - strange, the card itself is not powerful at all. The Ghostmare combo is overpowered but, not by the combo itself. Darkness and Time provides separately great Creature/Permanent control cards, plus a decent damage output as well. In many cases the spine of the Darkness/Time deck - the Ghostmare - can be countered but, eg. the Steal/Reverse Time spam gives a hard time. On the top of it, Sanctuary shuts down the Ghostmare combo but, it can be stolen as well.
Possible solution: such cards would need an alteration. Eg. Shard of Wisdom gives the damage bonus and the magick status
but, removes immortality.
3. Overpowered against certain decks - in my opinion, many cards are called overpowered only because they do "too" well against certain decks. This case doesn't mean a "real" overpower. Similar case if a card is powerful in itself but, it can be countered in many ways.
Example:
Black Hole - sure it's annoying, especially if played early. However, whil'st it can ruin a Rainbow's strategy it does little to no harm to a Mono/Duo deck. Discord is the opposite, hinders a lot a Mono but no real threat to a Rainbow.
Example#2:
Otyugh - no doubt it's among'st the best creature control cards but, it can be countered in many ways. Basicly every kind of creature control cards work well against it.
Example#3
Poison effects - many decks are vulnerable to poison for sure. In theory, the only counter card is Purify (which is way less situational right now since it can remove poison from a creature too and it counters Shard of Sacrifice). In practice, you can (1) outdo the poison damage (2) out-heal the poison (3) fight with your own poison against it. NerveToxin is annoying indeed, but, it's not easy to make a Dune Scorpion work (especially since it is a prone target to everything). A little side-note which makes a connection between the cathegories. If a card called 'Maturation' existed with a bonus of +1|+1 for a creature it would be Context-Overpowered since it would give a possibility for building a Mono-Time NerveToxin deck.
Possible solution: no change is needed.
4. Comparison over/underpowered card - certain cards are over/underpowered because of each other. However, the gameplay and the certain elements' other cards "wash away" the difference. (See example!)
Example:
Fog Shield/Dusk Mantle (Or the upgrade pair of course) - The former costs 2|1 quanta, the latter one costs 6|4 and gives only 10% more chance for evading an incoming attack. In theory, Fog Shield is way more powerful and makes Dusk Mantle obsolete. In practice, the latter one is a Darkness card - that element has good synergies with other elements, a cheap and decent weapon, useful creatures... an "underpowered" shield compensates the other cards. (Especially since with Steal, one can get the opponent's shield too...)
Possible solution: in most cases, no change is needed.
5. Underpowered card - some cards with are rarely show up in decks because they give too few for a too high cost. Some of these are too situational.
Example:
Deja Vu - in practice, you'll have 2 pcs. of 1|1 creatures (2|2 if upgraded) for 2 quanta in 2 turns. Sure you can buff the Deja Vu before copying it but, that's outmached by the fact that it can be destroyed too before it "breeds".
Example#2:
Shard of Bravery - costy, and gives real advantage in rare situations. Besides, Fire is a "fast" element in itself, doesn't really needs a speed buff.
Possible solution: increase effect / reduce cost.
6. Context-underpowered card - some cards seem to be okay but it's hard to get much benefit out of them or, compared to their effects they are too easily countered.
Example:
Anubis - as a creature, it's expensive. Its skill needs Ether (which is, if unupgraded, expensive too), so, you need both Time and Ether to use Anubis well. In my opinion, both elements have better synergies with others than with each other. Many Ether creatuers are already immortal, which lowers the usability too. In a Rainbow there are so many better places for that 8 time quanta than playing an Anubis... Still, the card is a good idea but it gets underpowered beacuse the clumsy usage.
Example#2:
Firefly Queen Deck - a good old great idea, once the Queens start spamming the Fireflies and (if unupgraded) the Rustlers drive back the quanta and the Hope is out, it's almost unbeatable, especially if the deck has Feral Bonds too... However, there are way too many counters against it. The Queen is still expensive, Tower Control/Black Hole hinders the quanta production for it. The flies are vulnerable to most of the controls and the shield effects. Many cards, like an Electrocutor, an Otyugh, a Fire Buckler etc. can ruin the whole strategy - a strategy which is more complex than many other decks. Not the Queen is underpowered - the Queen
deck is. In a Rainbow you need a lot of quanta to make the Fly-spamming work (plus, you need the Queen herself early...)
Possible solution: major change is needed in cost/effect or work mechanism. For example, if the Anubis had the ability which Shard of Wisdom has
now...
7. Broken card - not simply overpowered, it ruins the game balance. (Of course, an underpowered broken card is not a real problem since noone (or very few) uses it.)
Example:
Shard of Focus - since it fits any deck (any!!!) and provides the possibility of destroying 3 permanents (or more if it gets damaged) it greatly hinders deck-building creativity. Before this Shard, one had to think about whether he/she wants permanent control in the deck and if the answer was yes, only certain elements came into the picture. Opponent has one turn to do something against the Shard which - especially in Rainbows - can show up in the very first turn! Sure, it is "normally" overpowered too because its insane versatility (a few examples are Rage Elixir, Gravity Pull, Catapult). But, the real problem is the concept of it.
Possible solution: remove or drastical change.
Sorry for the long post
Here, have some water