Let me clarify that the criteria for an attack to make my list is that it is generically good in any character, that means no character only or cards with character only abilities unless they are worth using outside the character as well.  Further I am excluding mill cards as only a couple classic characters involved mill.

Chaos Fire
Here's a little guy that's very easily overlooked.  It's got below average stats, ranged status, and the usual worthless anti-ranged effect.  So why does it make my list?  The trick is in that cost.  It is an arbitrary life payment.  That is to say there's no requirements, no restrictions, you just pay any amount you want.  Why is this good, well the easiest reason is a little ability called desperation.  This card allows you to run cards with amazing desperation effects that are worthless other wise and know that all it takes is to draw a Chaos Fire and you can put yourself into desperation at your leisure.  Now this isn't the first or only card that is allowed such unrestricted life payment, but I believe it is the first for most of its symbols and some, such as life, can actually make use of the effect end of it too.  What do I mean?  One of the biggest problems for life gain decks is that you can't heal past your maximum vitality.  Any additional healing you could do is generally wasted.  With Chaos Fire you can potentially turn that extra healing into damage on your opponent.  Got the ability to heal 10 more vitality but already at full, chaos fire away 10 and maybe add that 10 onto the damage of your next attack.  Worst comes to worst you just heal back the 10 and no harm done.  Defiantly a lot of potential in this over looked card.

Killer Vortex
I don't generally care for 3 damage attacks even if they are off middle, 3 control and only 3 difficulty.  But what makes this card worthy of a look in your deck is not the card's admittedly above average stats, but it's effect.  Getting this attack into your momentum, as with most such cards, is free and only relies on it dealing damage which shouldn't be too hard.  Once there however this thing truly shows its power.  For every copy of this in your momentum EVERY high zone attack you play gets +2 speed.  Everyone single one, at no cost to you.  For decks featuring a lot of high attacks this is incredible.  Get a few of these in there and the boosts add up quick, soon it's almost as if every high attack you play is unblockable before you even modify it further.  It's also worth noting that this card matches all 3 symbols exactly with a certain potential game ending high attack known as Concealed Shallow Swipe.

Kuchu Soul Smasher
At face value this card isn't much to look at, it features the low damage of 3 I despise so much and comes at a hefty 5 difficulty price tag.  But like Killer Vortex the trick lies in that effect.  In a deck that runs many character cards Killer Vortex's effect can consistently pump itself by +6 for no significant cost to you.  Obviously if you want cards removed from the game that's an extra plus but even outside of those decks a 3 mid 9 damage attack is pretty impressive, consider that it came at the cost of only 5 difficulty and featured a solid 3 control and it's even more impressive.   You may need to find ways to get it to land but it's always nice to have big cheap hammers in your deck.

Rolling Buckler
There it is again, that 3 damage, it seems awfully prevalent in this set for some reason.  Once again though some incredible effects are here to the rescue.  Based on stats alone Rolling Buckler is well below average, it's got good speed and a rare low zone aim, but 3 damage for a 4 difficulty 2 control is usually grounds for chucking in the bargain bin.  What saves this card are its 2 abilities.  First off is powerful 2, a simple effect and yet an appreciated one.  Prior to the new sets Good had only 2 attacks with powerful, Sumo Smash and Dixie Twist, both not particularly impressive and both only powerful 1.  To Good this card is one of their first true kill conditions.  Air and Life already had some nice powerful options but it never hurts to have another.  Then there's that other E, for a momentum you can play any enhance on any foundation in your opponents staging area paying no costs.  Um, wow much?  Suddenly your opponent's best friend just became his worst enemy.  I could go into a list of some of the best enhances but just take my word for it, this can be VERY handy.

Valkyrie Turn
Here is another card that I think has snuck under the radar, many people not realizing how good it actually is.  The first thing to realize is that unlike some of Morrigan's cards you do not have to be below max vitality to use the effect.  This a big thing because it basically means no matter the current state of the game this card guarantees a 6 vitality swing in your favor.  At full just burn them for 6, at lower then full you heal up and maybe do a little burn.  Maybe your lower than full and they're without hand but they've got all sorts of E based damage reduction out, then activate its E for X = 0, the enhance step immediately ends before they can reduce it and they're forced to take that 6 straight on.

Big Cyclone
As a normal attack I'm underwhelmed by this card, but where this card intrigues me is in the side board.  You see with defender of the empire getting banned there's a good chance hand discard will be on the rise again, not likely to the extent it once reigned but enough that packing some anti-hand discard can be quite handy.  What makes this anti-hand discard stand out from some of the other options we already have available is four-fold, one is the element of surprise, unlike foundation based prevention your opponent won't know you have it until it goes off and he's wasted his discard effect.  Second is that it's nearly impossible to negate, there's lots of ways to negate foundation effects but almost nothing stops Big Cyclone from hitting the table.  Thirdly it's also a card that punishes your opponent.  Preventing discard is all well and good but if your opponent is going to be as insidious as to nuke your hand why not throw your gigantic 10 damage packing Sasquatch foot right into his face as payback.  Finally one of the biggest advantages it has over a lot of the other anti-hand discard is that this thing is still a very potent card even if the hand discard never comes.  4 speed 10 damage is very solid and it has a pretty potent block on top of that.  Sure it's mid and that 2 check hurts, that's why I wouldn't necessarily main board it, but it's nice to have a useful card even when the discard cards don't get played.

Bat Spin
I really didn't want to mention this card because it seems like the most over hyped new attack in the set but it does deserve mention among the top new attacks.  It's pretty much a staple in Demitri but even outside him it can't be ignored that for 4 difficulty and 3 control your getting 4 damage, decent off mid speed, and a potential 4 vitality swing in your favor for only a single momentum.  Even when your without momentum this card is solid and that alone says something about it.  I don't know that I buy into the "staple in all decks" hype I've been hearing but it's certainly worth a look in most decks.