Creating a "main antagonist" is one of the finest "high wire" balancing acts for any GM. Create them too weak and your sessions will feel like an anticlimax. Too strong, invincible (or just plain annoying) and your players will lose engagement. The trick is to find a balance that will build towards a satisfying resolution.
One method you can use to keep your team motivated while forestalling the main confrontation is to use a "lieutenant"; a powerful enemy that they are motivated to defeat but who turns out to be merely a minion of the chief. The party has the satisfaction of partially resolving the plot but are well motivated to fight on in search of the true enemy.
While you would never want your antagonist to be unassailable, there is no harm in making your party work hard for their victory. The first attempt to defeat them need not be the successful one, provided you give the party some hope for the future.
Weakening the antagonist for a future attempt might be one outcome. Being unsuccessful but learning what will be needed next time could be another. It doesn't hurt to teach your players the value of a wise retreat to regroup. Revealing, for example, a crucial weakness or vulnerability may be the reward for that first unsuccessful attempt and shouldn't discourage players from seeking another.
One of the joys both of gaming and GMing is creating a believable dynamic between player characters and the NPCs who stand in their way. Provided you give some thought to the game mechanics, you can create confrontations that are both tough and rewarding.
Happy Gaming!
-Stolph
PS: Any ideas for main antagonists who will frustrate and thwart your party? I'd love to hear about them. Just reply to this email!
