While your threat is 40 or higher, Angbor the Fearless gets +2 and does not exhaust to quest.

"Four thousands I sent marching from Pelargir through Lossarnach two days ago; and Angbor the fearless rides before them."
–Aragorn, The Return of the King

At the end of the round, discard Galadriel from play.

Response: After you play Galadriel from your hand, search the top 5 cards of your deck for an attachment of cost 3 or less and put it into play. Put the remaining cards back in any order.

Boromir gets +2 while defending against an enemy with an engagement cost higher than your threat.

Response: After Boromir takes any amount of damage, ready him.

Sentinel.

Response: After an enemy is revealed from the encounter deck, ready Gimli.

"Give me a row of orc-necks and room to swing and all weariness will fall from me!"
–The Two Towers

Ranged.

Response: After Legolas participates in an attack that destroys an enemy, draw 1 card.

"He stands not alone," said Legolas, bending his bow and fitting an arrow with hands that moved quicker than sight. –The Two Towers

Combat Action: Ready Háma. He gets +3 until the end of the phase. At the end of the phase, discard Háma. (Limit once per round.)

"I am the Doorward of Théoden," he said. "Háma is my name." –The Two Towers

Response: After an enemy is added to the staging area, exhaust Anborn to give that enemy +5 engagement cost until the end of the round. Then, deal 1 damage to that enemy.

"Now I have him at arrow–point." –The Two Towers

Response: After Mablung enters play, choose an enemy to get +5 engagement cost until the end of the round. Then, you may engage that enemy, or return it to the staging area.

"But still we will not sit idle and let Him do all as He would." –The Two Towers

Response: After a Rohan ally you control is discarded from play, exhaust Gamling to return that ally to your hand.

"...we have a thousand fit to fight on foot," said Gamling, an old man, the leader of those that watched the Dike. –The Two Towers

Combat Action: Discard Grimbold to choose an enemy engaged with a player. That enemy cannot attack that player this phase.

Grimbold's men turned aside and passed round to a great gap in the wall further eastward.
–The Return of the King

While there is a hero in your discard pile, Prince Imrahil loses the ally card type and gains the hero card type.

"We must gather all of the strength that we can find.
–The Return of the King

Action: Spend 1 resource from a Rohan hero's resource pool to put Elfhelm into play from your hand under your control. At the end of the phase, discard Elfhelm if he is still in play.

"...my lord sends word that we must set ourselves in readiness; orders may come for a sudden move."
–The Return of the King