To set the stage, we have a 5th level party of 4 characters, a ranger tank, shadow monk, tempest cleric, and blast warlock. Against them I arrayed a CR 7 Black Dragon, 2 CR 2 Ogres, and an environment that was relatively open. The terrain included multiple 10x10 or 15x10 areas of standing water, open skies, and a single 40x60 building. Mist lightly obscured the area. That might seem like a very difficult fight (actually it comes in just under the "deadly" designation in 5th's xp budget for encounters), but my players are pretty tough and wielding a couple powerful magic items. Plus this was the "big fight" to conclude Act 1 of my campaign, so I was prepared to kill someone. They eventually triumphed without losing anyone and had a great time.
Illustration by Ben Wooten
The fight gave us some strong insights into how dragons work in 5th:
1. Their damage is high for their CR. At CR 7, the Black Dragon is capable of dropping a full hp 5th level character in a single breath weapon or attack round on average dice. I'm talking a breath attack averaging around 50 damage, swings that hit AC 17 on average and do 12-15 damage a piece. Just brutal. Their defense is about where you'd expect, excellent AC and high HPs, but not out of line with their CR.
2. They are highly mobile, which makes them far more deadly than their numbers might otherwise indicate. With Speed 40 and Fly 80, the dragon was able to move easily around the battlefield, picking his targets, lining up breath weapon shots, and taking advantage of weaknesses. While environment and initial positioning are always going to be important to the difficulty of a combat, with dragons this is doubly so. A large space can allow them to make full use of their movement, even flying away while their breath recharges. Compare that to a CR 9 frost giant, which basically has to close to melee and swing away. I know what my party would rather fight. This makes them far more deadly against the typical, melee-oriented party than a comparable CR creature.
3. The Lair rules are great. Mileage may vary between creatures but for the black dragon at least, the lair rules provide interesting changes to the combat field without necessarily causing damage. This allows for more tactical play against the party, and forces them to get outside their base strategies. Importantly, the lair can't be attacked or disabled. An allied wizard could have been disabled by the party, but lair actions are just something the party must endure or avoid, which added to my tactical options as the DM.
4. Dragon fights feel suitably epic. It's "Dungeons and Dragons"; the dragon fights had better be a big deal. Your players want to fight a dragon, you want them to fight a dragon, and so the creature rules had better live up to the hype. 5th ed dragons, especially when combined with lair and legendary actions, do just that. Their high offensive and defensive numbers, combined with their high mobility and tactical advantages from lair and legendary actions, make fighting them a battle your players will remember.
My party is already looking to find and slay more of them. As a little bonus to the treasure, I threw in some of the "Dragon Corpse" rules from Hack & Slash Master, which my players really enjoyed as well.
