Here are a few ideas for some new traits I think could bring some new teams and strategies to Gems of War.
Indestructible - Cannot be Devoured
Phase Shift - X% chance to avoid magic dmg
Armor Will- Magic dmg reduced by 25%
Stone Will - Magic dmg reduced by 50%
Granite Will - Magic dmg reduced by 75%
Mana Manipulation - Double ally gem masteries
Serenity - Allies cannot be silenced
Protector - Recieve 50% of dmg taken by allies
Taunt - Must be targeted by enemies/ allies have stealth
There are some really great ones in here!
I like the protector one.
You forgot to mention Mana Guard.
Mana Guard - Cannot be mana drained
There are also a bunch here, some of which the devs actually managed to add to some varient in 1.0.9. Random Trait Ideas
more interesting ideas. both posts @Havoc made got some nice ideas IMO
I like this one, but perhaps Incorporeal would be a better fit?
I think it would work well with ghostly troops like Sunweaver. 
This one has me thinking. What if all troops had a built-in negative trait to set them a bit more apart? Things like:
Squishy - Take 50% extra damage from skull matches.
Slacker - Decrease attack by 1 after dealing skull damage.
Coward - Flees from battle when an ally dies.
Braggart - Reduce all stats by 3 when not placed in first position.
Hoarse - Start battle silenced.
Clumsy - Entangle a random ally after dealing skull damage.
Distracted - Lose 1 mana whenever an ally casts a spell.
Unstable - Deal 3 damage to all allies on dying.
Dying - Lose 1 health each turn.
Pain Link - Deal 1 damage to adjacent troops on receiving damage.
Mana Leak - Gain 1 mana less from [color] matches.
Mana Burn - Receive 1 damage for each point of excess mana gained once spell is charged.
Doomed - Receive a random negative effect after matching 4 or 5 gems.
Tainted - Immune to positive effects.
Tormented - Negative effects never expire automatically.
Yep, I know, looks utterly horrible at first. I mean, who would really want a Squishy Goblin or an Unstable Goblin Rocket, right? It would allow for some extreme buffs to balance things out though, like giving a Dying troop a very high health pool or an appropriate spell (deal missing health as damage to target, restore half missing health). Wish there was some kind of sandbox for weird game rules, like the Tavern Brawl in Hearthstone, I think I’d enjoy giving it a go.
I like idea of fear like status effect ok spell cast. Target an enemy or put it on random enemy. Effect of fear of an allied troop dies while fear is on a troop that troops flees from a battle. 10% chance to cleanse every turn (like for other stat effects)
I like the ideas of weaknesses. I think might be a fair while before something like that comes into the picture but that’d be an interesting twist
Another idea:
Steadfast - Troop can’t be knocked out of position.
Would this mean the whole team couldn’t be shuffled as well, a la Dust Devil?
I think it would mean the team would be shuffled around a card. I like the idea of it, but with the DD nerf it doesn’t seem like it would be valuable anymore
I would like to see the goblin lord trait changed to be more of a “if there is another goblin on your team that goblin takes damage instead”. Cause you know a goblin king would have some meat shields
The way I see it, your team would be immune to Dust Devil if a steadfast troop was in the lead.
If not, as Mufasha suggested, they would stay put while the other cards switch places.
Regarding its value, I suppose that depends on the amount of swap spells added in the future.
Color blind: 10% chance to collect mana when matching gems that don’t match that troop (but worded way better)
Stingy: collects mana first regardless of troops above them.
Regardless of position.
Disguise - only possible with a hero in the team. Team make-up may be different than what is Scouted.
Transform x - When this creature dies or has x amount of health it dies and then summons x creature.