I admit, I've screwed it up before. Let me see:
(Notes)
1) it's been four rounds, with the first one being the "suprise round" - I tried calling it round zero for a bit, but that's not how 5e works. So it was R1, and everyone but Thorbin, Lex, and Jathlin (and all the Sahuagin) were surprised.
2) The CrabRider has an action to command the crab to move or attack (recharge 5/6). He used it in Round 1, and Round 4. Round 2 and 3 he fired his blowgun.
2) The Crab has done nothing but dash. I was sure when I started that the crab would have a climb speed, but it doesn't. I'm not going to make it roll (let's say that the combination of a crab's 'grip' and the nature of the cliff makes the DC low enough not to bother). But I will make it climb at half speed. So 30 feet per round.
(Audit)
Round 1) It started 5 feet below the surface. This is why Lex wasn't surprised. He saw something down there. Then round 1 started and the CrabRider commanded it to climb. (His turn). The crab climbed to 10 feet up. Then it had its own turn, and climbed to 40' up. (Post OOC#188 calls this 50 feet, wrongly.)
Round 2) Rider fired his blowgun. Crab climbed to 70' up. (Post OOC#188 calls this 110 feet, wrongly. Post OOC#217 calls it 80 feet, also wrongly. Huh. Mistakes.)
Round 3) Rider fired his blowgun. Crab climbed to 100' up. (Post OOC#252 has this right).
Round 4) Rider finally recharged his command and commanded a move. Crab climbed to... 145 feet. Post IC#88 calls this 150 feet, wrongly. So do my notes.
So... 145 feet up at the end of round 4. Everyone is going for round 5 now, unless I've really screwed something up.
I have to admit, I've been confused many times while running this combat. It's probably a bit too big for any sane person, even if it were run IRL and with miniatures, it would be ambitious. It's a bit much for PBP. But it has taught me to keep better notes, so I should be making less mistakes going forward.
One of my mistakes early on was thinking that I could get away with handwaving all the non-pc-related combatants. But that was just too difficult with players, very rightly, trying to save NPCs who were in danger (causing them to turn away from 'their' enemies to fight NPC's enemies, if you see what I mean) therefore I needed to do it 'properly'. So my son and I ran the fight IRL, but we did extra rounds (the first time) but again the actions of the players (including Throbin's shocking body count) changed everything, so I had to backtrack and just play it out one round at a time. (This is one of the reasons that a few guards seemed to come back to life. I thought they were goners for sure, but the orca and shaman were killed much faster than I thought they'd be, and the guards had survived only one round of attacks).
Anyway, we've got it down now. If everyone can get their turns in relatively quickly, I'll see if I can get this round rolled as fast as possible.