Posted this on another forum a while ago:
myself said:
I'll differentiate between strategy (overall method of going about your goals, campaign-level) and tactics (method of going about a particular encounter):
Being able to dictate when and where encounters will take place and under what conditions, is the most important strategically. Usually, this is done with a mix of:
good information gathering/scouting (including magical means like Scrying),
transportation (especially transportation that puts you out of reach, or brings you into encounter range, of opposing forces whenever you so choose, such as Teleport),
and methods of preparation for diverse situations (buffing routines, item crafting, gathering of allies).
Gaining extra actions for team hero, and/or denying actions to team monster are the most important tactically. This is rather complex but will include:
winning initiative (acting first can often mean you also act last, giving you more total actions than the enemy),
simply granting extra actions or actions out of turn such as by White Raven Tactics or Celerity,
buffing (which makes actions more meaningful or in some cases is what makes an action possible in the first place, e.g. with flying opponents you need flight to reach them, incorporeal opponents need magic etc.),
bringing in reinforcements with their own sets of standard+move action (such as through ally class abilities [animal companion etc.], summoning, necromancy...),
battlefield control (enemy movement restricted, be it by Solid Fog or Thicket of Blades plus Stand Still),
debuffs (enemies can't act meaningfully, such as through blindness effects, or are at least forced to act less meaningfully since their abilities are drastically reduced),
quickly killing opponents by whatever means necessary,
Bringing opponents over to your side.
Very broad, very general, I know.
You might have noticed that on the strategy issue, a noncaster can contribute much less than a caster. Sure, skills like Gather Information and Diplomacy can help you prepare, but they're no substitute for divination or mind control/necromancy/planar allies/etc., respectively. Furthermore, not much is stopping a full caster from investing a few skillpoints here or there, further restricting the mundane niche here.
What's more important, countermeasures to what the opposing force might be doing strategically are almost entirely relegated to magical power.
Tactically, now, the mundanes have some powerful options available. Killing the opponent outright is a good method of denying actions, and uberchargers aren't the only ones who can do this. A certain amount of buffing and debuffing can be done by nonmagical means, and some battlefield control, especially in the tanking variant, is possible too.
Nevertheless, all these can be done as well or better by casters. Regardless whether you turn into a melee monster and start hurting people, cast save-or-dies, or simple optimized damage spells, casters can kill things, there's no doubt about that. Moreover, buffing and debuffing is really their province, and Black Tentacles is battlefield control at the very least on par with an enlarged Spiked Chain lockdown Fighter.
But casters can play with the action economy even more effectively using a whole bunch of tricks at their disposal, which mundanes simply have no access to: they can go first more easily using the right spells, they can simply be untouchable until they choose to engage (and sometimes remain untouchable even then).
They can make more use of the actions they get through ongoing spell effects, spells that make use of swift/instantaneous actions (mundanes don't have much use for those), spells whose effect can be invoked as a move (such as Flaming Sphere) or even free action (such as Cloud of Knives).
Even if mundanes can emulate these things through magic items, it comes down to a caster who must provide these.
To use an oft-quoted metaphor, mundanes get their pick of a hammer, a screwdriver, or a pair of pincers. Maybe even two of those, and some mundane classes throw in a ruler and pencil as well, or a wrench etc. Some problems they'll be able to tackle with their chosen tool(s), but not all. Creative players can make many problems look like a nail if all they have is a hammer. But that's all they get.
I'm tempted to now go on to say that mundanes get one tool, while casters get a whole toolbox. But that's not even true. Mundanes get one or two tools alright. But casters get a tool factory, and the necessary workbenches, drawing rooms, and skilled workforce to dream up and create any tool they damn well please for the situation they're in.
Don't believe me? Still don't believe me? Need even more convincing? OK, that's enough, I think. (and yes, I think it's rather easily conceivable that a given Sorcerer build might have all of these on hand without cramping his style in the least)
And on top of that, casters still get a bunch of premade quality tools to handle a lot of situations - or not get into them in the first place.
Sure, some of this only holds true from the mid levels onward - but that's an accepted fact, and kind of the basis of this thread, isn't it?