So first guestion is, that does Grimbeorn The Old follows first player every turn when first player token moves to the next player, or does it stay with current first player´s control at the end of the game.

And another guestion: Can i use Durin´s song after shadow cards has been resolved from the enemies to raise my defense by 2?

#1: I don't know.

#2: Short answer: Yes.

Long answer:

The rule book lists the 4 steps of an enemy's attack:

1. Choose Enemy

2. Declare Defender

3. Resolve Shadow Effect

4. Determine Combat Damage

And the rulebook says, "Players may play event cards and take actions at the end of each step." So you flip over and resolve the shadow effect. Before you substract your character's defense from the enemy's attack, you can play any action (such as Durin's Song) to boost your defending character's defense, and then you determine combat damage.

You would count your defending character's newly enhanced defense stat, not what it was originally.

Looking at the wording, I'd have to say that he stays with the first player. My reasoning: He joins the first player as an ally once there are 8 resource tokens on him - this is a constant passive effect. Nothing I know of removes those resource tokens, hence when the first player changes, Grimbeorn will move to that player as well.

Thanks for answers