Video Preview: What Does Challenge Rating Mean?

My player's PCs are all pretty powerful. I can make an encounter deadly, then double it, and they still come out fine. They only death they've had was from a catoblepas' gaze attack, and even that was immediately reversed by a spell in the next round. Their ACs are all pretty high, so only things like spells and breath weapons* really matter. Lately I'm using monstes that are more creepy than dangerous, like Spawn of Kyuss. *Not necessarily dragons, but things like chimera and hell hounds too.

Some more secrets to balance encounters is use action points for legendary creatures. Have this scale with party size, and have them use any ability, not just legendary actions during fights. Also alternating initiative helps a ton.

One thing I think that's important is to pick fun monsters, or to modify a monster to make it fun. If you're not excited about a monster encounter then make it exciting by adding interesting terrain or monster abilities. or maybe another monster to combo with the first one.

All of your points are very true. My five level 8 players were surprised to learn that the white dragon they defeated last night in Rise of Tiamat was CR 17. Using the Lazy DM math, 5x8=45/2=22.5. I knew this would be a tough fight and at least one character might die, but I also knew that my group of very experienced players could win. It was a tense battle, but fun!