I have been having pretty good luck with Krystenax/Krystenax/Dragon Soul/Elemaugrim I have lost around 5 or 6 battles out of 200 against that team this week. Krystenax must be full traited because you are taking it’s colours off the board and Elemaugrim must have the impervious trait. The only time I cast Elemaugrim is when it will kill both Krakens because if it misses it can fill Krakens but if it’s only Mab it’s fine because she can’t do anything to Ele or Dragon Soul. I also never take skulls because with Krystenaxs flying she can’t be entangled and with stone skin and Eles third trait she can take a lot of hits.
What I do is take a purple asap to get enchant going on Nax and then rush up either Dragon Soul or Nax depending on the board if the board is full of blues or greens I just rush up the Nax. I only ever cast Dragon Soul and 1 Krystenax I always keep a Nax full for when either Troll or Kraken gets ups. If Troll is up I remove greens or if Kraken is up I remove blues even when the Troll is dead I still remove blues because it usually gives Kraken a lot of extra turn damage and it fills Mab and allows her to cast and get an extra turn.
If you can remove enough blues and greens then the Kraken/Troll team sucks and can be beaten easily but you will get bad boards and the ai will get lucky sometimes and it will still destroy you