Ok, I think is more balanced. He can even be used without any doom cards (although why would you? it'd be like taking gandalf without his pipe).

Why would Saruman, from the thematical aspect of the card, or any of his toys, reduce the threat of other players when playing Doomed cards?

- Saruman is the head of the order (interaction with Istari keyword?)

- Head of the white council

- Is the maia sent by Aule and has a lot of knowledge about the rings (interaction with Artifact keyword?)

- Has a commanding voice hard to resist (some event card such as flame of anor?)

I'm really hoping that Saruman will appear in this cycle somewhat tied to the Master keyword (or Doomed, that would be good too). The themes and usage of the word "master" (as in The Master Ring) and the idea of power to control others is a very important one in Tolkien's writing, and is perfectly represented by Gandalf and Saruman. Gandalf is a "good leader", not adscribing power to himself but instead renouncing to it, and while he's powerful, he's more concerned with helping others reach their goals and achieve power themselves, while he stays as a pilgrim, a wanderer. Saruman is the complete opposite. He couldn't trust anything to anyone, and had to control everything himself, thus becoming a lord with a stronghold and army, a master with other minds and bodies to control for his own goals. He becomes a "master" in the sense Tolkien uses the word, more related to the theme of slavery rather than being a "master at something". (On this note, only Bombadil could truly call himself Master as he was the sole, and only a, master of himself.) So yeah, as soon as I saw the One Ring player card and the Master events we got in the deluxe, I knew the themes of power and corruption were lurking behind them, and so I really really hope this cycle will bring us Saruman and other cards and themes related to powerful, dangerous artifacts like the Palantiri and the art of ring-making.

"Why would Saruman, from the thematical aspect of the card, or any of his toys, reduce the threat of other players when playing Doomed cards?"

Have you not played the Voice of Isengard expansion? Notice the theme of doomed cards ? (as well as isengard?).

Does this not represent Saruman's role in forestalling the enemy? For those who don't know, Saruman didn't just arrive and turn. He fought against Sauron for about 1700 years before his mind began turning to possessing the ring so... reducing the Doomed element actually seems pretty spot on from this perspective (and you know, tying it in to all the literal cards which are obviously thematically tied to Saruman being Doomed...).

As far as all the other things, yes obviously some more istari cards would be great.

I am not saying it is not thematical that Saruman interacts with the Doom keyword, I think it is actually very thematic, very much like Grima does.

What I don't see thematical at all is that it reduces other players threat, I don't see but a pure mechanical intention to make doom more playable in multiplayer, I see no theme there.

But hey, that is my opinion.

I see mass threat reduction as both perfect mechanical and thematical fit. Mechanical fit is obvious, thematical fit is that Saruman was working with these forced for a long time and mastered them, so he is able to mitigate the downside while working with them.

From a thematic perspective it represents Curomo's ability to study and understand the methods of Sauron. Not only does it aid directly against Saroun, prolonging each player's time by reducing Doom from the encounter deck, but it also allows the players to utilize all the methods and knowledge Curomo has gathered, in the most effective way (yet still dangerous, which is perfect for Saruman).

I'm not sure if they'll think of a better mechanic.

And thematically, honestly I think it's genius. Threat represents the most vulnerable way to lose the game for the players. Threat represents The Enemy's awareness of you the heroes. Saruman has the ability to obfuscate that, to buy time. Sure there are cards to reduce threat, but only a few heroes actually reduce threat, and it is either small and negligible (beregond, galadriel) or costs precious actions (merry).

This version of Saruman would have a much more significant impact (particularly in encounter decks that have doomed). But even outside those decks it allows you to utilize the dangerous knowledge Saruman has gathered, for little cost (in some cases no cost).

To me it feels like that it represents Saruman's ability to DIRECTLY counter Sauron. When Saruman first came to middle earth, he went into the east (and perhaps the South?) to confer with the blue wizards and gain their insight on the state of the realms under Sauron's control. He then went on to directly help Gondor in many conflicts (fun fact: gained Orthanc that way). And even when his mind changed towards gaining the ring, he was still using his knowledge to counter Sauron (drove him out of Dol Guldur by the "machinations of Saruman").

What better ability to show he is the head of the order, perhaps the most significant challenge to Sauron during his time than by safeguarding each player's threat from doomed?

You can achieve essentially the same effect with less text with the following:

"Reduce the X value of the first Doomed X triggered each round by 1."

And wording it this way makes it seem like Saruman is better at using Doomed effects, rather than reducing everyone's threat, which seems counter to the Isengard archetype.

Actually he should increase other players threat by corrupting them

One other possibility is to make him a hero that can not have other heroes in his deck... To emphasis his solo attitude.

Reducing threat is not counter to the Isengard Archetype, it is counter to the Valour archetype

Correct. The Isengard Archetype is raising threat. Reducing threat is essential to that archetype. Either way the function of his ability is the same. But I think it should be once per phase, I've actually already tried this out in a couple of games now (well, 2 anyway). It didn't "feel" overpowered to me (play a lot of nightmare).

It doesn't feel overpowered, because it doesn't gives you an advantage, it (partially most of the time) mitigates a disadvantage. Plus, it is printed on a very costy hero.

Well, a wizard is never late...

Challenge of the Wainriders