This paired with Steward of Gondor is amazing. If you have a deck with Leadership Denethor and Any Éowyn with the two attachments I mentioned above, (one being SoH) you can give Éowyn resources to still buy stuff, and she can commit 7 each round.
Song of Hope
Attachment. Cost: 0.
Attach to a hero. Limit 1 per hero.
Action: Spend 1 resource from attached hero’s pool to give attached hero +1 until the end of the phase. (Limit 3 times per phase.)
The Black Serpent #82. Leadership.
Why not just use Celebrian's Stone rather than using Steward's resources on temporary willpower? — NERD 178
Maybe you're already at your restricted cap (Celebrian's Stone is restricted this is not)? Maybe you did have Celebrian's Stone in the deck alongside this (Celebrian's Stone is unique, this is not)? Maybe you want +3 Willpower and are willing to pay the cost? There are situations where this isn't a bad pick, it's just expensive (Steward makes this less of an issue). — Erathis 1
It's also a Song, which has strong synergy with several other deck types, particularly Hobbits with Fireside Song. — kjeld 310