I've never dabbled much in custom factions, probably because the official ones are so well balanced and fun, anyways...
My two cents on the Fairies. They seem a bit over powered. Mainly in the fact of Swordsman, Events and Rema.
A note: The way I've helped to determine the use/balance of abilities is to look at their cost. I use a system I call the AV+Health system, where you use the total of the Attack Value, health, and ability value and compare it to the cost of the unit for the total score. It's not a perfect system, but it's something I use in my head to help determine the usefulness of units in a Reinforced deck. Usually cost is within one or two of AV+Health for commons. A good ability would add one to the AV+Health score, and a great ability would add two. So for example, your Swordsman have a cost of 2, an AV+H value of 4 and an awesome ability, so that would add two more (I want to say 3, but we'll leave it at two) to AV+H, making them have a total AV+H of 6. That's insane.
A two life, basically two attack, free movement, AND attacking during movement? So, it's a hit and run, wall crowding, rushing unit? It just seems FAR overpowered for a common. This is an ability I would see on a Champion. If you want to keep it's ability, reduce it to one health, or alternatively you need to tone down the ability. Either change the "at the beginning of your attack phase, you may move each Swordsman..." to two, or remove it all together. Even without the ability for free movement, they're still slightly overpowered for a common. The biggest avenue for abuse that I see is that since they move at the beginning of your attack phase, and can attack at any time between movements, means they can move in, attack twice, then move out of the way for a ranged unit behind them to attack the unit behind the one they just killed. Add on top of that you can move EVERY one you control, and that's disaster. In an average game, that would mean you would probably be moving 6 of your units per turn. That is devastating by itself, not coupled with the fact that they are 2 attack and can move in between attacks.
Rema is essentially a 6 cost, since you're always given her magic back when she dies. Plus, the ability to roll 2 dice against 3 enemies at full range is also extremely strong. That means when Rema Dies, you have the possibility to gain 4 magic; one from her, and 3 from common units you can easily kill with that ability, since it doesn't state clear spaces. I'd recommend changing it be more like a bomb.
"When Rema is destroyed any card adjacent to Rema receives one wound marker."
I feel that's a bit more balanced. That way she is still threatened by ranged units. It's not really fair for a unit to have no weaknesses. She's a 3 AV 5 Health ranged unit, that gives the opponent a VERY negative penalty for killing her. The way it's worded, there's no way for the ability NOT to trigger, because unless you're using a specialized unit, the unit that gets the kill is always going to be in range of the ability. If you want to leave the ability as it is, and not have it set up like the bomb, at least reduce it to two spaces, and change it so its one die against 3 commons, OR two against ONE Champion. Possibly being able to roll 3 free, 2 AV attacks against all the enemies Champions on the DEATH of a unit is way too strong. Just as 2 AV against 3 Commons. Another possibility:
"When Rema is destroyed, roll a die for each card within two clear straight line spaces of Rema. On a result of 3 or higher, that unit receives one wound."
That way it is still a powerful ability, but can be countered by ranged units, and is dangerous for you as well because if Rema gets sniped in formation of your units it could hurt you as well. I've specified "card" so that she damages walls with the explosion as well. I'd remove the clause about her going to your magic pile, because that breaks the whole idea that summoner wars is balanced around. She already has a negative ability for killing her, and you're denied her magic? Ouch.
Finally, the events. I wouldn't have originally had a problem with these until the app came out, because I hadn't had much experience with Tundra Orcs. I always wondered why they didn't have magic drain, until I realized that Freeze does the same thing, just with a different benefit. It immobilizes your enemy and forces them to spend magic. While you don't gain any magic from the transaction, you can the advantage of either immediately denying the enemy two magic, or allowing yourself to gain the upper hand in placement.
Poison not only disables the enemy, but also damages them, so there is a rush to remove it. The wording also needs to be fixed, because right now, technically, the unit takes a wound every turn, meaning one wound during that units turn, and one wound during the Fairies turn. Just seems too powerful there. I like how it's balanced a bit by the "adjacent" clause, but you need to change "card" to "unit." Card can be a wall, and that again overpowers the card.
Plus you have to look at it like this. You have the ability to deny 6 magic from an enemy just with Poison, along with debilitating and wounding the unit. THEN, you're able to deny 4 more magic. That's 10 magic denial from event cards. If your units were weaker, I'd be okay with that, but with your powerful units, and awesome events, it's just imbalanced.
Which brings me to Reflection. Yes, your unit still takes damage, but at the 'cost' of giving back that damage. Not to mention, it's use is always predicated by an enemy attack. You're going to use reflection when you're going after the enemy summoner in a big push. Other protection abilities still allow for damage to be done, be it in Cloak of Shadows, which allows you to damage on a six, and that still only protects one common, or one champion/summoner for TWO magic. Summon the Night is a protection event as well, but it still allows the units to be attacked by a melee unit that is placed well.
Reflection again is just too powerful, and especially for two of them in a deck. Maybe reduce it to "adjacent units receive wounds equal to the number of wounds dealt to your unit" or make it universal in that "whenever a unit you control is attacked, the attacking unit receives one wound marker after the attack is resolved."
Tidal Wave I don't have much of a problem with except that it seems like it's given too much range. If it's going to hit everything in that space, give it a range of something like 3, that way even if it's placed on the front of your board you can't hit the back rows of your opponent. If you want to leave the range, put in a clause stating something like "this card can only place up to 6 wound markers this way" or "this card can only damage 3 units this way." "this card deals one wound to any common or champion within 7 straight clear line spaces, and one wound to each common or champion unit within 7 straight line spaces. This card may not wound an enemy unit if it must pass through a wall first."
It needs some finesse, but I like that last wording the best; my intent with it is that Tidal Wave does one to every unit in a line, and two to the first unit it hits. Also it would stop at a wall, which I feel makes sense.
I hope you take my considerations to heart, and know that I didn't intend to come in here and rip your faction apart. I really like the idea behind them, it's unique and something Summoner Wars doesn't already have. I'm a bit harsh on it because if I was only allowed to say one thing I love most about Summoner Wars it would be that it has impeccable balance. Even with the 16 different factions and all the reinforcements, the only card I've found even remotely close to being unbalanced is Gror, but still he is moderately balanced out in that he has the possibility to wreck your own units as well.
I used to do a lot of custom M:TG cards, and when I started out balance was a huge issue for me. Of course, balance isn't a strong suit to M:TG because ultimately your strategy comes down to how much you've spent on boosters, but that's a discussion for a different topic. It's hard to not over power your own creations, because you love them. :P You want them to be strong and to win. I believe you mentioned something about the Bronze Mechs. Honestly, take the overpowered-ness of the Swordsmen, and split that ability into a Bronze Mech common. Take out the free movement and attacking during movement, and give that to a Bronze Mech unit. It seems like it would fit the theme in that the ability could be called "Clockwork" and the common that has it is a 1AV/1H. Then it makes sense that they move outside of movement phase, and can move and then attack.
All in all, a great start. It needs some tweaking, but I'm excited to see what you come up with next, and I'm excited to see the route you take with the Bronze Mechs.