pawsplay said:
Unless they're going to promote solo play, "counts as two monsters" and "is slightly more dangerous" work out to exactly the same thing.
Not really. Right now in 3e, the only real way to increase the power of a creature is to either add hit dice or templates. Hit dice increase the hitpoints of a creature while also increasing the saves, BAB, and skills of a creature. Templates normally add a bunch of powerful abilities to a creature.
Rather than make a creature slightly more dangerous, they normally have the effect of making a monster a LOT more dangerous. Often a 2 CR increase in a creature will increase the to hit of a creature by 6 or 7. Its AC might increase by 8 with the right template. Its saves probably go up by up to 4 each. Its DR might go up by 5. It might gain resistances or immunities to energies. That combination of things decreases the chance of PCs attacks to hit (by up to 40%!), the PCs spells from affecting them, the amount of damage they do, the ability to affect them at all as well as the amount of damage needed to defeat them.
When what you really want in a hard monster is about the same chance to hit them and affect them (maybe a little bit harder, but more like 5% harder) but for them to have the ability to stand up to the amount of damage done by an entire party of adventurers for more than one round. It really ruins the effect of a major enemy when they die in one round when they take 150 combined damage in a round when everyone in the party hits them.
So, typically, you'd want what 3e currently can't provide: A monster capable of withstanding the hits of the entire group for 5 rounds of combat. Assuming a party of 5 PCs each capable of doing 20 damage on average, you'd need a monster with over 500 hit points to survive this. Any creature with over 500 hitpoints in 3e has at least 40 hitdice giving them at LEAST +20 to hit(likely closer to +30). It isn't unreasonable for a party of 8th level characters to have that as an average damage. However, they'd be killed REALLY quickly by any creature capable of power attacking for 10 and still hitting most people on a 2. Plus, even if you could tone the to hit of the creature down to a reasonable level, it would still be a fairly boring fight as the monster attacks once per round and then the PCs act 5 times then back to the monster again.
So, that's the point of solo and elite monsters. Creatures who survive longer and might have the ability to do something that feels threatening to multiple members of the party at once.