This session was a chance to try out Lair Powers. I set up several of them for the Purple Worm - an effect that knocked everyone prone if they failed Dex checks, a rocks falling from the ceiling damage effect, a caustic slime burning anyone attacking the worms effect and a swarm of tiny wormlings swarming everyone effect. I didn't want these effect to be overwhelmingly powerful, but on reflection, I could have probably bumped them up a bit.
There aren't stats for a Purple Worm in the materials available yet, so I grabbed some different powers from existing creatures, and tried to make a CR 8 monster. The party is level 6, but there are 5 of them, so I thought this would be a good challenge.
Lesser Purple Worm
Gargantuan Monstrosity , unaligned
Armor Class 11
Hit Points 135 (10d20+30)
Speed 30 ft., burrow 40 ft.
STR 20 (+5) DEX -3 CON +3 INT -2 WIS +3 CHA -4
Senses Tremorsense 60 ft., passive Perception 13
Challenge 8 (4000 XP)
Amphibious. A lesser purple worm can breathe air and water.
Multiattack: The Lesser purple worm can make one bite and one sting attack per turn
Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 8) piercing damage plus 5 (1d10) poison damage, and the target is grappled (escape DC 13). Until this grapple ends, the target is restrained, and the worm can’t bite another target.
Sting. Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 22 (4d10) poison damage on a failed save, or half as much damage on a successful one.
Swallow. As a bonus action, the worm can make one bite attack against a Medium or smaller target it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside the toad, and it takes 15 (3d10) acid damage at the start of each of the worm’s turns. If the worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.
On reflection, Str and Con should have been higher, and damage probably should have been higher across the board. I was also thinking about adding an automatic "Overrun" attack for anyone close to the worm.
For the wormlings, I just used the Giant Toad stats.
Couple of notes from the combat:
The Eldrich Blast knockback is pretty powerful, although houseruled that it doesn't effect the Mama worm on the fly. Sure, nothing in the description says that there are size restrictions on the knockback - but as I said in the session "That's why I'm the DM."
I ruled that the rogue couldn't sneak-attack the Purple Worm, since the worm has tremorsense and knows exactly where everyone is at all times. Once Hilbo engaged it in melee, I allowed a sneak attack, but I'll have to review exactly how that works.
My basic policy as a DM is that if a rules questions comes up, I make a fast ruling that keeps things going forward. If somebody knows the rule, I listen, decide if it makes sense, then make the call. At the end of the session, if anybody has an issue with the ruling, we discuss, check the book, and decide on how to run it going forward.
In the case of the sneak attack and knockback calls, nobody seemed too bothered by them, so we didn't re-address.
Now comes the BIG THING. Hilbo used his magical item, his action surge and the -5 attack/+10 damage ability. That gave him 4 attacks at +5 to hit (+5 from str, +3 from proficiency bonus, +2 from his magical maul, -5 for power shot), each doing 2d6 +17 damage (+5 from str, +2 from maul, +10 from power shot). He hit 3 times in the first round. When the worm attacked, he used a Riposte and hit, then he got 2 attacks the next round, hitting with both. He did 124 points of damage total. Whoof. So if somebody bitches about fighters being underpowered, cordially invite them to shut the fuck up.
Of course, the worm is a classic brute - low AC, high hp, and this is an attack pattern basically designed to work against it, but still - very effective strategy.
The rest of the wormlings weren't much trouble - Hunger of Hadar and the difficult terrain formed by the dead Mommy worm made them come in stages, and the Eldrich bolt knockback pushed them back into the Hunger area.
The worm only got 2 lair effects off, the knockdown and the caustic slime attack, and the one attack it got off that hit didn't do too much damage, as dwarves have resistance to poison damage and advantage on poison saves.
All in all, the combat ran smoothly and quickly. The Roll20 app is much improved in terms of speed of use, and the Initiative tool is handy for keeping track of init. Each character got 1050 xp, which brings Korrum and Hilbo near level 7.
The rest of the session was pure role-play, which was great. I ruled that Wanderer, who has minor illusion magic and sleigh of hand proficiency, was able to keep his thieves tools and a dagger on him, as they weren't stripped to the skin, and Sinder can summon his sword at-will. So we'll see how they do with a classic prison escape scenario next session.