Hearthpwn

Hey, I have a question.
Situation : 
We play Rogue, and we have Rogue Galakrond, the Nightmarein our deck. We play Swashburglar and we get Galakrond, the Unspeakable. When we invoke, which Hero power will be triggered? Both or Rogue ? And both Galakrond will evolve? 

Thanks.

This has been answered by the Devs, only your main Galakrond will evolve.  On top of that, Galakrond or anything with the Invoke Keyword cannot be randomly generated or Discovered.  So the only class that may be able to do this reliably is Priest, who can copy cards directly from an opponents deck or hand.  

I still think that the priest-one is FAR better than the Rogue-one; i think that even drawing 4 cards (and rogue-invoke cards are right now pretty MEH) for 0 mana is by far not as good as this one. Priest lacks right now in one thing, and that's card draw: this draws no card, but it gives you a priest minion, and that's nearly as good.  And being able to destroy 4 minions on board is often better than the rogue-one. This nearly works as the priest-DK.

Still: right now we know nothing about invoke, we first need to see all the cards.

An upgraded, yet aggressive, Sprint on legs,

So does Rogue for example get two Legendaries in addition of this or just this and Waxadred?

Yes, each of the E.V.I.L classes will be getting 3 legendaries - their Galakrond hero card, a legendary dragon, and a third legendary. The other 4 classes will be getting the typical 2 legendaries.

This is specifically the Rogue Galakrond. Each Galakrond will be different depending on the class.

His Hero Power is : 2 Mana, add a Lackey to your hand.

"The dragon to end all dragons, Galakrond, manifests as five brand-new Hero cards, one each for the Warrior, Warlock, Shaman, Rogue, and Priest classes. Each version of Galakrond comes with a powerful Battlecry and Hero Power. However, the recently awakened Galakrond is still growing in power, and the League of E.V.I.L. will need the help of dragon cultists to Invoke Galakrond and release his full potential."

Source: https://playhearthstone.com/en-us/blog/23200870/announcing-descent-of-dragons-hearthstone-s-newest-expansion

so is this neutral? all the class cards reference galakrond so it makes sense if it was, but this has the rogue border. I guess we've never seen a neutral legendary hero before, but the border is the exact same as the one for valeera.

It is only for the EVIL heroes so Warrior, Rogue, Priest, Shaman and Warlock. 

Look up my comment for an answer.

Each Galakrond is a unique (different) legendary, hence there is 5 different Galakronds this expansion.

However, it appears as if Blizzard will give you all 5 for free.

The hero power for this is  2: add a  lackey to your hand

What does Invoke mean ?

I think its like a C'thun thing 

Using specific cards invokes him. Cards like Shield of Galakrond or Seal Fate. It's a bit like buffing C'Thun (wherever it is).

Invoking also seems to trigger the hero card's hero power (wherever it is).

Invoke is a universal buff applied to your Galakrond which triggers the specific hero power of your class Galakrond. Also every 2 invocations it doubles the effect of your Galakrond (such as draw 1 becoming 2 then 4 for rogue). At the final level, Galakrond also equips a 5/2 weapon.