... here are a few awesome links do enhance Tomb of Annihilation (or just simplify your DM's life) ...
Thank you for these links, I am definitely finding these useful as I read through them. Here is another that may prove useful --
https://newbiedm.com/2017/09/30/newbiedm-review-tomb-of-annihilation/
Anyway... I do have some doubts myself ... Does the sparse encounter rate make things too easy? Basically, everyone is 100% full for each and every fight. Did anyone use any kind of house rule to overcome that?
Was thinking to roll encounters for a few sessions at a time and then sort them by Total Challenge Rating. After a few attempts, except for a Zombie Trex and a Red Wizards roll a hex or two off from Port Nyanzaru, most of the other rolls made sense and fit well. In particular, I like the encounters like the Triceratops which gives a party the chance to both avoid a fight and gain some treasure.
If there can be a few undead, eblis, or insects (e.g., giant wasps) that can hit the party with everything they've got the same day that the party meets their destination -- usually a marked location -- then I think that's the best a DM can do to raise the difficulty.
In practice and without game theory, does use of class abilities and magic just bypass all difficulty of the Exploration part of the game? It's too bad to ask players to don't play classes that would just "skip" great portions of the difficulty?
People on those blogs you linked to agree that some Ranger powers are a bit too-useful, but I wouldn't worry about it too-much. The surrogates content provided by WotC includes a tabaxi Ranger who starts with Swamp and later adds Forest, as well as a Tortle Circle of Land Druid who starts with Coast.
Flying races should probably not be allowed. I think the way the Adventurer's League explains to players that they can pick one book besides the Players Handbook to flush out their characters makes sense for this adventure. My thought was to allow the same rule, but to disallow the Elemental Evil Player's Companion, or to only allow the spells and not the races from that book. Unsure how Xanathar's Guide To Everything will affect this, but it probably won't and the good news is that most players are going to want to choose it as their second source.
By mid-level Druids and Wizards are the most-difficult to control as they will get out-of hand, but this is true in every campaign and every adventure. DMs should already be equipped to handle these situations.
Did anyone make calculations on how many encounters are needed between Port Nyanzaru and Omu for the characters reach the expected level?
If you follow the guidance on page 84 of the Dungeon Master's Guide, then I would like to see a party average around Level 3 upon completion of Mbala (with the variety of random encounters and the smaller awards from the marked locations around the two rivers sprouting from Port Nyanzaru leading up to that Level 3). The party must travel to Shilku Bay (and complete both dwarven quests) to attain Level 4 and to Jahaka Bay after taking out 3 pirate ships and their crews, bringing their total to 4400 experience. The only single-day marked locations that will bring a full party to Level 5 before Omu would be to take down both the Hvalspyd and Nangalore. Even if the party has another 400 or so experience to get to Level 5, the gargoyle attack at Kir Sabal and the trek to Omu should get them there. It looks to work out rather nicely -- it was certainly well-designed.
I'm probably DMing for a party composed of 6 players, how hard is to amp up the difficulty for those? Any tricks on adjusting monster quantity on the fly?
The adventure adjusts to this size of a party without any modifications. There are a few scenarios such as Camp Righteous and Firefinger that allocate 2 goblins or 2 pterafolk per character. The tricks will mostly involve managing the Druids, Wizards, and other module-breaking character builds.
It's just me or the book states in Chapter 3 that "the Red Wizards have 2 cubes" but they don't actually tell which ones? We're supposed to choose which shrines players will "skip"?
The DM can decide which shines the Red Wizards visit. The first shrine where the party successfully takes a cube, another shrine (probably on the other side of the city) has its cube taken by the Red Wizards. If the party encounters the Red Wizards, they can take that cube, but that's unlikely. It's more-likely that the party will waste at least one day on two or three shrines --- maybe only successfully taking one or two cubes. Each day that goes by, the Red Wizards have a 25 percent chance of taking another cube. RAW says to determine which shrine this is taken from randomly, but I might suggest pitting the party on one side of the city and the Red Wizards on the other side until they work their way towards each other.
Did anyone do a nice miniatures list needed to play this?
Haven't really seen a list per se, but I did find --
http://dnd.wizards.com/products/tabletop-games/miniatures/icons-realms-tomb-annihilation -- and ---
http://www.beholderthebargains.com/d-d-minis-tomb-of-annihilation/
Did you guys let players have multiple guides? How did they get enough gold to fund this?
Yes, with the usual quirks of handling multiple NPCs including competing guides and side questers. The party can easily get gold early-on by betting on races, by capturing animals to sell to Merchant-Prince Ifan, or by the normal methods of acquiring treasure and selling off unneeded goods. A Level 1 party shouldn't be able to steal from the merchants, and especially not the Merchant Prince Villas, but a Level 3 party, with the aid of one or two helpful Merchant Prince(s), might be able to sneak quickly into and out of one other Merchant Prince's Villa with some goods.
In the method I laid out a few pages back in this thread, the party might start off with River/Flask for free to Fort Beluarian, lose them, but pick up Qawasha/Kupalue there and head back to Port Nyanzaru to get Eku. Then the party could adventure for awhile with Qawasha and Eku at the same time. Eku is a bit too-powerful to keep too-long, so I would leave her to her wiles after Mbala and Orolunga are complete, but she can make an appearance later if you'd like. The dwarves are needed for the Shilku Bay locations, which require even more gold to get out of the Bay of Chult in the first place (travel by ship and paying off the dragon turtle). I would save Azaka and Faroul/Gondolo for the adventures on the east side of Chult. I would pair Salida up with Xandala in order to team them up against the party, preferably hitting them when Artus Cimber and Dragonbait are around. In other words, the party can pay for multiple guides in stages -- increasing them over time and occasionally shedding a few here and there.
Guide-wise, Eku seems a bit "unfun" as she has too many support tools. What difficulties (as DM) did you find using any of the guides? ... What's the real (practical) chance the players choose the "lame" guides, like Gondolo or the Yuan-Ti?
I like to make it difficult for any character to get a Charisma of 20 by limiting starting characters to a maximum score of 15 at campaign start. In other words, restrict potential Loyalty to 8 at Levels 1-3 and Loyalty 9 at Level 4 unless a guide's personal quest is completed or the party somehow saves a guide's life.
Eku will have a Strength and Dexterity of 10 with a proficiency in quarterstaff. For some reason, if she does join the party into a marked location or special area with a lot of combat (Mbala counts), then it may be difficult to explain why she can take so many hits. For Mbala, I rolled a random encounter with another party of explorers (and rolled that they were in good health and headed there). Their tribal warriors were used as fodder in the battle, and Eku stayed to the sidelines.
Introducing Azaka, Hew, Salida, or Shago early-on is also something I wanted to avoid. In a more-natural manner, I introduced them subtly in the background -- only bringing them into the foreground after the two main rivers leading from Port Nyanzaru are completed (possibly with the exception of Firefinger). I introduced Azaka, Faroul/Gondolo, and Shago after the Jahaka and Shilku Bay areas were completed. I also reintroduced Eku at that time. I think it may make sense to swap the locations of Firefinger and Ataaz Muhahah on the map, putting Muhahah over the River Tiryki and Firefinger just west of Muhahah's original location.