Definition of Synergy

[Hyroen]

Due to some odd discussion during the Trials, it has come to my attention that the definition of synergy in the eyes of some individuals may be a little off. If it were me, I'd certainly like to be enlightened.

Would you consider that these cards have synergy?
Echooo.... echoooo..... echooooooo.....
Simple Air mechanics. Chaining implies the act of playing the same card in a sequence. And yes, it stacks.

ART SOURCE was edited a bit by me as well.
3! 6!! 9!!! 12!!!! 15!!!!! 18!!!!!!
Up to 60 damage with chained Fury, but time them right, otherwise you'll get a simple Fire Bolt!

ART SOURCE (http://www.sxc.hu/browse.phtml?f=view&id=1143736)
What would be your definition of synergy? (This does not mean copypasta definitions of synergy from the internet. xD)

What cards would have synergy in the game? Do they follow your definition of synergy?

Discuss. ^_^

[Jenkar]

To me, synergy is very simply two (or more) cards that, together, have an effect greater than the sum of their parts.
Take SoP and flooding. SoP gets strengthened by flooding (card text)
One big problem in this definition is the line between Synergy and Combo. *warning : totally personnal view here*
To me, a combo is where the sum of part has a great effect that does not enhance the power of one (or two, or x) cards in the combo (ie, is equal to the sum of their parts). Take the classic instosis combo. Is Mitosis-SoR a synergy? No, because mitosis doesn't get a bonus from SoR more than any other ability. Nor does SoR. (Note that the time creature-SoR relation *is* a synergy, because SoR is stronger if used on time creatures)

[Freefall357]

Cards that benefit from each other but do not rely on each other have synergy.  The link can be direct, or indirect.  When used alone they are effective, when used together they are greater than each one individually.  This is different from a combo where you NEED both [or more] cards in a certain order to get the function of the pairing.
A good example of synergy outside of Elements is in a CCG where creatures/vehicles/whatever attack and defend, hitting each other.  A card that gives your stuff +1/+0 and the enemies stuff -0/-1 would be a synergy.
If your cards can all work together and benefit from each other in any order and with any being completely removed it is a very synergistic deck and will be powerful in every game...If you need X card to play Y card so you can get Z effect that is a combo...while generally far more powerful than a synergy, it can completely fail, leaving you with cards you can not use, or that are sub-standard when used alone.

I would call your example a combo.  Take one of the pair out and how useful is it?  If you fail to draw any Furys, but get 4 Echos, are you still efficient and effective?

If I had slept in the past 48hrs, I would try to elaborate...or at least sound coherent...as that is not the case, I will stop and we will see what other people say 
I too am curious what people say.

TL;DR:
Synergy - Cards that benefit from each other but are not dependent on each other.
Combo - Cards that REQUIRE each other, often in a certain order to be of value.

[OldTrees]

Default: The value of the sum is equal to the sum of the values of the parts
Synergy: The value of the sum is greater than the sum of the values of the parts
Disynergy: The value of the sum is less than the sum of the values of the parts

Fury only has synergy with itself and cards that trigger when the opponent is dealt damage.
Echo has synergy whenever multiples of a card are played consecutively.

Both have synergy but Echo has much more synergistic combos with much greater synergy.

A Forced Combo results when an UP card has a sufficiently strong synergy with another card that it becomes usable in that combo.

[dragonsdemesne]

Synergy is when two cards work extremely well together, better than either individually.  Antisynergy is when they don't, and work better in separate decks.

Synergy example = Discord and Black Hole.  Discord scrambles quanta so that Black Hole takes more of it away.
2nd example = Antimatter and Liquid Shadow, making the attacking creature heal you and damage its owner.
3rd example = Fire Shield and Maxwell's Demon.  Once an attacker is damaged a few times, maxwell's demon can kill it.

Antisynergy example = Dissipation Shield and Sanctuary.  Sanctuary prevents Dissipation Shield from working.
2nd example = Antimatter and Firestorm.  It isn't as bad as my first example, as there can still be reasons to play both, but normally you wouldn't use both in the same deck, because you don't want to kill your opponent's antimattered things.
3rd example = Shard of Gratitude and Shard of Sacrifice.  The SoGs will damage you if you play SoSa.

[Rutarete]

Yes, I would say your example cards do have synergy. On a side note, it reminds me of MtG's Izzet ability of replicating.

I think synergy is any combination of things - cards, in this case - that you can call a strategy.