DMs! Have you ever had a “boss encounter” turn into a cakewalk? What happened?

[n0nym]

I've had at least one BBEG slain too easily. The guy was a powerful elf archmage with a Candle of Invocation. I wanted the PCs to come into the room just before the wizard lit the candle with a patronising speech. Turns out PCs love to interrupt BBEG when they talk and before I could say anything the archer PC screamed "I shoot before he can talk". I had him roll Initiative and a few good rolls later, the wizard lay in his own blood (he took EXACTLY 99pts of damage from 4 arrows, despite having Shield and Mage armor up).

From this day on I've never done the same mistake. Now I do "cutscenes" where the PCs can't act. It's sometimes frustrating for them but the story is a bit more cinematic this way.

Oh and regarding liches, unless the PCs cast Nondetection (which they never do) I *always* assume that the lich has full knowledge of their actions and location. It can never be caught flat-flooted.

 

[Dioltach]

2nd edition psionics. Killed the campaign's BBEG deader than dead in one round.

 

[Sadras]

The most recent incident involved my first ever use of a Remorhaze (it wasn't a BBEG, but it was supposed to be a deadly fight according to the DMG). The beast tore through the snow-covered earth, PCs fells varying heights 10-50 feet either into freezing water or onto outcroppings of the torn up earth made by the creature via its entry.
The creature won initiative and I rolled to attack and missed. Wizard went next and casted Polymorph, I again rolled low, thereby turning my CR11 into a seal. Combat over.

TLDR version: Terrifying introduction, creature attacks & misses, does not save against SoS, combat over.

And here is the kicker - I was DMing the PC because he was absent that day and that spell made the most sense, having known the player, his style and the character's spell list.

 

[Stalker0]

Been on the other side of blowing up a DM’s plan- again, due to dice. In fact, it was 2 times, in two different adventures ...with the same PC.

It was a Human Ftr/Cleric of Tyr in a high-level AD&D campaign. She had 2 weapons, both quite powerful: a Mace of Disruption and a Vorpal sword. She used the Vorpal sword to behead one of the two BBEGs the party faced...on round 2. This panicked his partner in evil, who then kept making baaaaad decisions as the rest of the party took him down.

The second time involved a highly improbable die rolling sequence. On an evil demiplane, the party encountered a Lich and his Death Knight attendants, and combat ensued. My Cleric drew the Mace...nat 20.

Because of the nature of the plane, there was only a 1-in-20 chance the Mace’s special powers would function. I rolled, and succeeded.

Because of his nature, there was only a small 1-in-20 chance the Mace’s special powers would affect the Lich in particular. I rolled, and succeeded. The Lich was annihilated in one shot.

I asked the DM what the odds were that her patron Tyr would notice this feat across time and space. His response: “1%.” The d100 roll came up with a 1.

I asked the DM what the odds were that her patron Tyr would personally reward her. His response: “1%.” The d100 roll came up with a 1.

Exasperated, the DM proposed a few personal rewards Tyr might bestow in her. I suggested one might be +1 level of Fighter (which would raise her Att/rd from 3/2 to 2/1). His response: “Sure, 1% chance of that happening.” The d100 roll came up with a 1. My DM groaned.

In a shaft of light, Tyr popped into the demiplane- time stopping the combat- laid his hand upon her head in blessing, then disappeared.

That extra full attack per round really came in handy.

For those keeping score, the chances of all of that happening after the nat 20 was rolled is .00000025%!!

 

[Stalker0]

Wizard went next and casted Polymorph, I again rolled low, thereby turning my CR11 into a seal. Combat over.

Having dealt with polymorph quite a bit lately, I will say that while exceptionally powerful, its not nessarily instant game over. It usually means the party gets a solid round of attacks on the creature, and then it goes back to work. The BBEG is still heavily hit, but it usually gets a least some chance to do something once the first attack drains the polymorphed hp.

I mention it because at first when dealing with it I threw up my hands and said "combat over", but having experienced it a few times, its not quite as bad as that.

 

[toucanbuzz]

We ran Out of the Abyss, and my players have come to expect epic things with epic adventures. So, I opted to let players run the demon lords in a battle royale. They did such a great job beating the crap out of one another that when it came time to face the winner (Yeenoghu!), it was the least climactic and lamest battle of the campaign. He was taken down by a Wand of Magic Missiles. A lame wand. But it's like the A-Team used to say: "I love it when a plan comes together." Their hope was the demon lords would weaken one another, and yeah, Colonel Hannibal, the plan came together perfectly.

There was a pause moment afterwards...was that it? Was it that easy? Where's the DM twist? Aren't you going to have him come back and we'll have an epic battle and probably some of us won't make it?

Nope, the epic part was having Orcus face off against Demogorgon and so on, and to let players know hey, sometimes things actually work out exactly like you hoped. Gratz players.

 

[Dessert Nomad]

The creature won initiative and I rolled to attack and missed. Wizard went next and casted Polymorph, I again rolled low, thereby turning my CR11 into a seal. Combat over.

Why is that combat over? As soon as they kill the tiny 'seal' hit points the rhemoraz is back in action. They'll get a round of doing a lot of damage to it, and the damage will carry over, but it's not instantly dead.

 

[Dannyalcatraz]

For those keeping score, the chances of all of that happening after the nat 20 was rolled is .00000025%!!

In a Dark Sun campaign, my dwarf died after a similarly improbable series of die rolls involving failed magic resistance and saving throws. The mathematician in the group- having witnessed both occasions- asked me if I had ever considered playing the state lottery.

I asked him if I could possibly have that much improbability left in my life.

He said probably not...which meant I was a shoo-in to win the jackpot.

 

[Inchoroi]

I'm actually thrilled when my players bat above what I expected them to. That means I can dial it up a little bit more.

My players have always had a tendency to hit above their weight, however. I'm just waiting for the time when their luck doesn't hold out.

Three words for you to consider:

Eleven. Player. Party.

I was not prepared.

Oh, my soul.

 

[pogre]

A Monk with stunning strike can take the air out of a big solo BBEG. I try not to use solos, but there are a surprising number of them in published modules.