Since this is more of a strategy question than a rules question, I didn't put it in the FAQ thread...

I am admittedly new to this game, but I'm having trouble seeing the value in removing a point of influence from the Shadow Pool. There seems to be very little effect, especially when Sauron is just going to have that fixed up easily on his next turn. Since there's usually a choice involved like "Gain 1 Wisdom or remove an influence token from the Shadow Pool", I can't see why you'd ever choose the removal unless you're maxed out on Wisdom. Am I missing something?

In particular the Black Plots for Stage II (Saruman and Denethor) requires high amount of influence in the SP (5 and 8 respectively). Further, the Plot Step comes before Sauron's Action steps, so denying him enough influence in the SP means one more turn when he can't play that Plot and in fact has to spend an Action to increase his SP again. Denethor Plot in particular is vulnerable, since Sauron's SP during Stage II is maxed at 8, so any reduction will nerf that Plot for another turn. Only other Plot that I've seen denied through reduction of the SP is the 4-influence requiring Yellow Plot at Barad-Dur, though only in Stage I. But Sauron in general wants to have three Plots at all times or if he doesn't, play a new Plot, preventing him from playing a Plot means another turn when a Sauron token doesn't move on the Story Track.

Another, less common use is the denial of certain Shadow Cards, but this is less effective since he can re-play the influence and then play the card, should it have a timing of Sauron's Action Step. Mostly I'd say, Shadow Pool reduction is key during Stage II, keep him either below 5 or not allow him to have 8 (which is also required for some of the better Shadow Cards). When playing Sauron, Thranduil is the one character I least want to see out there. Luckily, I think he is actually the rarest one. As for Wisdom, I've found that Wisdom 2 is okay, Wisdom 3 is about the max you'll ever need, for Sauron pumping up locations to 4 influence to make them perilous is just too expensive. So only Thalin really needs +2 Wisdom (but he needs +Wisdom BAD), for others, depending on the board situation, I'd be much more likely to look at reducing the Shadow Pool than picking up +1 Wisdom. Even getting chains of 3 influence isn't that easy or cheap and worse, they can still be cut down to one unless you have stretched your influence chains to two Shadow Strongholds (which I'll grant you is easy for the Anduin/Mirkwood locales).

Hmmm, I had considered how it'd affect playing Shadow cards, but not playing Plot cards.

There are two 4 Plot cards and one 8. I don't see that as enough reason to cause Sauron grief... unless you know he's holding them. I remember having a chance to see his cards last game and now I can see some more value in that action.

Stopping Shadow cards still seems more meaningful, especially in Stage I. There's still some utility in Stage II there too.

Trump said:

Winter Storm is one of my favourite Shadow Cards as Sauron, 10 requirement means I need to have full SP or losing two will mean I won't be able to play it this turn. And having 12 in the SP isn't really needed for anything (one Shadow Card that has to be played right after a Hero is defeated). Dropping Sauron from 5-6 to 4 or less has denial potential for a Plot, ditto for dropping from 8 to 6. Those Black token Plots together move that token 5 spaces and have high Favor costs to remove. As Hero, better safe than sorry, especially if the Black token is Sauron's lead token or the one that needs to reach Shadow Falls.