Prince Imrahil is a pretty good hero. The only problem I have with him is the limit once per round and the lack of the warrior trait. He's a solid attacker, defender, and has some good willpower, meaning his action advantage can take full effect. In the right deck (rohan) he can go completely nuts. With the leadership sphere and all-round stats, he can fill any role and open up Steward of Gondor, making him an excellent glue hero. The main reason he doesn't see much play, is the mere fact that he doesn't do one thing particularly well, so there will usually be better options. Good hero! Get the guy out of the binder and let him pull some weight.
Hero. Threat: 11. 2 3 2 4
Response: After a character leaves play, ready Prince Imrahil. (Limit once per round.)
But beyond, in the great fief of Belfalas, dwelt Prince Imrahil in his castle of Dol Amroth by the sea, and he was of high blood, and his fold also, tall men and proud with sea-grey eyes. The Return of the King.
David A. Nash
A Journey to Rhosgobel #50. Leadership.