Prince Imrahil is one of the characters from The Lord of the Rings that has always greatly interested me, so his latest hero card in the game immediately drew my attention. Ever since Prince Imrahil was released I've wanted to take advantage of his unique ability to sneak powerful allies in to aid with attack and defence. This deck is the result, and has been used with great success against the quests in The Sands of Harad (Éowyn is the best choice to be rescued first for the third quest), and I'm now putting it through its paces against a variety of other quests (most recently a solid victory over the Dunlendings in The Fords of Isen).
As this deck revolves around Prince Imrahil dropping allies into combat, you aren't looking for much to get going. However, you should mulligan for Steward of Gondor for Denethor so that you can use his ability to send a resource over to Prince Imrahil each turn. Visionary Leadership is important (for some quests it's essential and needs to be in your opening hand), but I've got through quests without it if enough allies get onto the table.
Gondorian Shield goes on Denethor, and Raiment of War can go on any of Déorwine, Defender of Rammas or Knight of the White Tower. Gandalf provides card draw and threat reduction, however threat isn't much of an issue as you start at 25 thanks to Éowyn's ability. Speaking of which, don't save Éowyn's attack boost for a special occasion - it should absolutely be used early if you are faced with a particularly nasty enemy.
Final thoughts: I'm sure some will consider the inclusion of Behind Strong Walls to be curious. Not only did I want to use a card that I have rarely used before, but it fits in incredibly well with Denethor, Defender of Rammas, Knight of the White Tower and Boromir.