This is a thematic deck that has Saruman teaming up with (exploiting?) his neighbors in Fangorn Forest.
The low starting threat allows you to really lean into using powerful Doomed effects, and helps buy time to rouse the ents and somewhat offset their tempo penalty of coming into play exhausted. By the time your threat level forces you to engage enemies, the Entmoot will hopefully be complete and the Ents will be ready to crush them.
This deck features a solid mix of questing power, combat, card draw, resource acceleration, multi-card scrying, and action advantage. It is balanced out by the fact that it can be a bit slow to get going, and that there is no threat reduction at all. A big part of playing this deck well is pushing threat increases to the limit while gauging the right moment to pump the brakes with Saruman's staff. I have won several tense games at 49 threat.
Use the contract to fetch and attach Keys of Orthanc. If you already have it in your starting hand and you intend to keep that hand, then attach Wizard Pipe instead. The latter doesn't shine here as much as in a Gandalf deck, but can still combo with Messenger Raven for card draw, or the various cards that reshuffle your deck for card exchange. In most games you will want a Resourceful and Treebeard in play ASAP. A second Resourceful is rarely worth it even with the Secrecy discount. Note that Treebeard is the only way to play Boomed and Trumpeted, which is why there is only one.
The deck was designed for solo play, but I suspect it could be adapted for multiplayer as well. In that case, the staff would become a top target for Word of Command, and you might even make it a 2x. In solo play it is more of a mid-game card, after you have run out of Doomed events and/or your threat is getting too high.