Intelligent Antagonists

Killer Queen by Louise Docker

There are pitfalls when the PCs face intelligent antagonists.
These pitfalls make playing D&D less fun.
An intelligent villain done wrong makes players think of railroads and that they're powerless to face the antagonist because of his knowledge, power level, etc.

Why have intelligent antagonists ?

I like intelligent antagonists and villains.
Role playing is about actions, consequences and choices.
How are the PCs challenged if the antagonists they face are dumb and passive waiting in a room while the PCs approach to kill them?

Omniscient

It's important to separate DM knowledge from antagonist knowledge.
The antagonist can't know everything, he is limited in information sources.
An intelligent antagonist tries to gather as much reliable information as he can, but he is fallible.

If the antagonist learns about the PCs and their powers, chances are a fight on his terms will be difficult as he focuses on the weaknesses of the group.

The antagonist usually has several contingency plans prepared in case something goes wrong.
This doesn't mean he necessarily knows of all the PCs powers or abilities.
A quest is a possibility to gain powers or abilities the antagonist doesn't know about. 

Power Level

Power comes in many forms, the antagonist can be powerful in combat or a brilliant politician, king, ruler, etc.
The PCs should interact with the antagonist on some level, preferable multiple times.

A large power difference leads to situations where the PCs don't bother stopping or talking to the antagonist directly.
Something like "He has like 10 levels on us, we're not supposed to fight him yet".

I think it's better to make the antagonist not that powerful but make the difficulty in fighting him come from his intelligence.

Character Knowledge

An intelligent antagonist uses the resources he has efficiently.
It is therefore important to communicate to the PCs what resources are available.

I usually make a list of available rituals to restrain the antagonist's resources.
The same can be done with supplements.
The PCs know these restrictions which allows them to better counter the antagonist's plans.

An example of abusing resources: they corner the antagonist only to find out he has a unknown or obscure ritual to escape.

Flaws

An antagonist may be intelligent but therefore not invincible.
He has flaws:

• character flaws like pride, wrath, envy, fears, shameful secrets, etc.
• combat flaws like vulnerabilities to certain attacks.
• caring about certain things, for example family, gold, reputation, etc.
• moral limitations, he doesn't have to be a complete monster.
  For example: killing children, killing innocents, etc. 

The PCs exploit these flaws to draw the antagonist out or to make him angry hoping he makes mistakes.

Exploiting some flaws is evil: putting innocents in danger or killing his family.
This poses an interesting question, how far are the PCs willing to go to beat the antagonist?

Repeating, Repeating and more Repeating

All the knowledge PCs need to outsmart the antagonist must be made clear to them.
So it's important to repeat this information several times.

Examples

I've had a wizard who was proud of his magic powers ignore a rogue in battle because he thought the rogue didn't pose any threat.
The rogue ended up stealing his magic belt in battle, severally weakening him.

Have you used intelligent antagonists in a campaign before?
If so, did they have any flaws that led to their defeat?