My current dnd group has been playing for years, while I am relatively new. Unfortunately, it seems that none of them have really ever put much stock in arcane/divine classes or abilities (this includes the current DM).
Our DM has recently decided he wants more arcane in his campaign and has asked me to help him organize magic heavy encounters (I am the closest thing to an arcane expert as we have, as far as rules and strategy go). I have given him lots of ideas for NPC arcane battle synergy, but it seems like my encounters are are always overshooting his target CR.
What are some general ideas for reducing difficulty by 2-3 CR without rebuilding the monsters. Lets say we take 2 Water Nagas (7HD) straight from MM. That would make ECL roughly 9. How can we get it down to 6 or 7, without changing their stat blocks directly?
I was hoping for something on the lines of this: when you approach the encounter, the nagas are already engaging some crabs. Then they will be softened up a bit, and down a couple of spells.
Or basically give the PC party one free surprise round.
Do these get closer to a CR of 7? How far away am I still ? any other imaginative ideas?