Wik said:
4) Strange terrain. Monsters in a fight scene where the environment plays an important role can keep the PCs looking away from Monster Stats. For example, fighting two Barghests is a pretty predictable encounter. Fighting those same Barghests during a hurricane is something entirely different.
This is an excellent suggestion!
I also second those who say to pick up a copy of the MM3. MM2 is 3.0, and 4 is... wonky. (It's best if you imagine a dragon-centric campaign, what with the dozens of pages related to dragon creature variants.) I dislike the new stat blocks as well.
I also have a player who literally has the MM memorized, and have made several adjustments to keep things fresh (coming up with "new" enemies that are really just MM creatures with one or two tiny things different, inventing new races that are really just MM races with a couple of cosmetic changes, etc.). The MM3 has also helped a lot.
But the main thing to keep in mind is to continue to allow Knowledge checks to reward players who invest in this skill - if someone has a +23 to knowledge (dungeoneering), they should be able to tell you just about everything about any ooze they come across, homebrewed or not. In other words, the
characters should be able to figure it out, regardless of what the
players know.
Also, for those talking about variant dragons, in general I'd say just to keep in mind that dragon CRs are lower than they should be because the game basically expects you to know what you're facing. Throwing a "wrong color" dragon at the party should be considered to have an EL something on the order of about 5 higher than normal.