Please share any examples where Grey Ker's ability to divide his turn really shines. I can't imagine much use of it.

The one thing I can think of is Grey Ker + Knight Class. Where Grey Ker can give knight possibility to attack twice. Works like this: Grey Ker approaches monster with 1 action, Knight uses oath of honnor and etc. After that Grey Ker continues.

But in most cases I fell it has no much use... any ideas?

The main advantage is in the Road to Legend app, where a monster group activates after every hero. You could use one of Ker's actions at the start of the turn, then a second hero could act in full, before the monsters got to act at all. Similarly, Ker could open a door and another hero could take a full action before the monsters responded.

I've also seen a lot of folks post that Gray Ker would make a decent Monk (either as Spiritspeaker or Prophet) but those posts are always a little funny on details. I guess the argument is it's always useful to have the healer spread their actions out a bit.

I don't know about a specific class combo, but Grey Ker's ability works AMAZING with any team that can recover stamina. Basically, works like this;

Grey Ker activates, fully exhausts (abilities, move, action etc) first action,
Bard activates, Grey Ker recovers fatigue etc
Champion Activates, gains valor etc, Grey Ker recovers fatigue
Grey Ker now has full fatigue again, activates for second action.

As 10355ts said, I think Grey Ker is really excellent in RtL, as he can regularly reduce the # of attacks and ill effects the heroes' suffer by performing an action at the top of the round.

Thanks for replies, maybe I should try RtL

Grey Ker has some good interraction with Shadow walker class, as you can attack, summon the Shadow soul, the interrupt his turn, other heroes can kill the monster, Ker takes his turn back, and can summon the shadow soul elsewhere.

He can uses the "hunter's mark" of the Stalker by leaving another hero make better use of the granted surge of the skill, or Exploit and weaken

Can be extend to any weapon that gives a usable condition (doom, weaken)

Could be a fun Bard to play as he can take his turn, activate a condition, take his turn back and change that song to another

Could be a fun shaman too as he can unactivate the Cloud of mists and reactivate it after all heroes have played so heroes do not suffer the surge needing to attack but monsters will

And I'm sure I'm missing more !