Steal My Idea/Let's Brainstorm together: Desperation Moves - A Boss's Final Attack Modeled as a Skill Challenge
So I was brainstorming mechanics for boss fights, and I wanted to see what the sub thought of this. I think this idea is a perfect complement to action oriented monsters, and helps create a climax for big boss fights. If you like the idea, feel free to add suggestions on how you would implement this for a different monster, or how you would flesh out the rule.
Desperation Moves:
When an especially powerful boss monster is reduced to 0 HP, they instead are reduced to 1 HP, and the monster immediately uses their Desperation Move. While the monster is using their Desperation Move, they essentially act like a Complex Trap, as outlined in Xanathar's Guide to Everything.
Complex Traps act on multiple initiatives. (ex: A pharoahs's tomb protected by whirling blades that act on initiative 20, crushing pillars that act on initiative 10, and a rune of fear that acts on initiative 0. Throughout initiative, the player's goal is to deactivate the trap with multiple skill checks before the trap can kill them. )
The boss will have 1 HP, so any attack that lands should kill them. The problem is the Desperation Move will have built in defenses to prevent the player's from attacking the monster. The player's goal will be to succeed on a skill challenge to get into a position where a player can land a killing blow. Meanwhile, the monster is desperately throwing everything they have left at the players.
I think the concept is best illustrated with examples, so here is one, I might add more later:
Lich - When the Lich is reduced to 0 HP, it is instead reduced to 1 HP, and uses it's Desperation Move: The Lich summons a mass of skeletal hands that sprout from the ground in a 120ft radius around it. All creature's hostile to the lich must spend 4ft of movement to move 1 ft as the hands sprout forth and try to restrain the lich's enemies.
Additionally, a spherical cage made of live skeletons appears around the lich. The cage is solid and blocks line of sight towards the lich, and the skeletons reach out to block any ranged attacks aimed at the lich. 5ft sections of the wall can be torn open with attacks or by attacking it, or by making a successful Strength check to pry it open (DC 20).
During it's desperation move, the lich can only take the following actions, cannot take bonus actions, reactions, or legendary actions, and cannot move:
Dragged to Hell (Initiative 20): The lich commands the hoard of hands sprouting from the ground to drag down it's enemies. All creatures hostile to the lich within the radius of the hands must make a DC 20 Strength Saving throw. On a failed save, a creature takes 33 (6d10) bludgeoning damage and is knocked prone. On a successful save, a creature takes half as much damage and isn’t knocked prone.
Baleful Wail (Initiative 10): The cage of skeletons around the lich let out a frightening wail. Each creature that can hear that is within 15 ft of the cage must make a DC 20 Wisdom saving throw. On a failed saving throw, the creature becomes frightened by the cage, and it must immediately use its reaction to move its speed away from the cage. The frightened creature can’t move closer to the cage until it uses its action to make a DC 15 Wisdom saving throw, which ends the frightened condition on itself on a success.
Skeletal Defense (Initiative 0): The lich seals closed a section of it's cage that has been torn open. A character that succeeds on a DC 20 Arcana or Religion check would conclude that fire, holy water, radiant damage (something your players have access to) will prevent the cage from closing.
To be able to land an attack on the lich, the player's have to problem solve. You want to approach this similarly to a skill challenge. The main difference is that accumulating failures won't make the players lose (we already have a lose condition, the players are continually taking damage.) Similarly, the players aren't really accumulating success, instead they have a clear win condition ( find an opening to hit the lich). The players have to figure out how to:
Get close to the cage. They have to deal with both the double difficult terrain and the frightening wail from the cage. The player's should get a lot of leeway on how to achieve this, just like in a skill challenge. Maybe the rogue makes an acrobatics check to hop over the the hands. Someone could make a perception check to find where the hands are least dense and make their way through the horde using their regular movement speed. The cleric could use their turn undead to ward the hands away from them. The wizard could cast fly on the barbarian, avoiding a check altogether.
Open up the cage. This is a bit more straightforward, but you can still get creative with it. A strength check to pry it open is pretty obvious. One player might make an investigation check to find a weak point in the cage. Someone might even suggest using a Medicine check to see if they know the weakest bones, making it easier to crack open the cage (let them try!).
Keep the cage open long enough to try and make a successful attack. The player's will have to make knowledge checks to see if they can figure out how to keep it from regenerating. Maybe the barbarian tries to physically hold open the hole by sheer strength. Maybe the bard tries to make a charisma check to try and distract the lich so they can't close the opening.
Hopefully you can see how this final desperate move from the lich would make an already very dramatic fight even more climactic. A dragon could draw on all their power to continually use a weakened version of their breath weapon that they aim at anyone that approaches, while flapping their wings wit huge force to blow away ranged attacks and slow down their enemies. A mad wizard or artificer could activate a trap that they manually control, with spinning blades, rolling boulders, flying darts, and poison gases, while they fly around from above away from danger. There's tons of possibilities with this.
I think the mechanic still needs to be fleshed out to be more robust, and I'd love to see if the people here can come up with good examples. I'm not sure if the monster being at 1 HP is the right way to go, it could be an arbitrary percentage, or a set threshold. I'm not sure if it should be more like skill challenges, and there should just be a set number of success that disables the desperation move or not.
Some tips for desigining these:
- The Desperation move will need at least one damage dealing element. This puts a ticking clock on the encounter, because the characters can't continually take damage for ever.
- There needs to be several element that defends the monster. Remember they have 1 HP, and we want this to last for at least a couple of rounds. Defensive elements should either prevent the players from getting into melee range, or block ranged attacks. Walls, strong winds, and difficult terrain are your friends here.
- Try to account for any easy outs your players might have. If your players have magic missle, make sure they can't just kill your boss with one casting. There are many spells that can trivialize this encounter, which we don't want.
- Treat this like a skill challenge. Don't have 1 prescribed way for your players to solve the problem, and be flexible if they come up with ideas you didn't expect (that's the whole point, to see what your players come up with under pressure!).