Phb page 37, on selecting languages, says:

Your character knows at least three languages: Common plus two languages you roll or choose from the Standard Languages table. Knowledge of a language means your character can communicate in it, read it, and write it. Your class and other features might also give you languages.

So your character gets at least three languages and also—so, additionally—what you get from other features like class or background.

The 2024 spell ends immediately if you deal any damage. So, also item damage.

5e RAW, they remain invisible. However, using the tinderbox will make noise so enemies will likely notice that.

In the 2024 rules, dealing damage (even if not by attacking) causes invisibility to end.

NOTE: both versions of the rules (see the oil item description) state that in this scenario, an enemy only takes damage if it enters or ends its turn in the oiled space. Starting their turn in the burning oil does not cause damage, so just moving out of the space will prevent the damage. The lighting of the oil also does not cause immediate damage

So far, I’ve played three sessions with three different groups. Haven’t run into big issues yet. Next session I will be using monsters from the new MM. I’m curious to see how the balancing turns out.

(assuming 5e or newer) You can’t true polymorph into Tiamat. The ‘aspect of Tiamat’ from Fizban’s is already CR 30, Tiamat herself is unstatted but obviously more powerful.

As a player character, you can only True Polymorph to a creature of CR 20 or lower

I can only say that in my experience, it works ok.

The current app is pretty useful. I can

• access all the content that I have bought on dndbeyond
• view the player characters that are playing in my campaigns
• play my own character(s) as a player, including dice rolls if I want. For major changes to my character it redirects to the website, but it handles all common in-play updates directly in the app (hit points, conditions, inspiration, equipment, preparing spells etc)

Be aware that you can purchase new content in the app or on the website, and the prices may differ between the two. In my case, the app uses Euro prices including VAT, while the website uses USD prices where the Sales Tax/VAT will be added on checkout. Most promotions will only work on the website.

To have one entity that controls all three(+) factions, they must have a goal that is not depending on the success or failure of any faction – it will most likely depend on the fact that there are multiple factions opposing each other. Who is gaining anything from chaos and discord? There are several candidates present in the book:

1. Captain Xendros. She is essentially a foreign agent that cares only about fish for her country, and magic items.
2. Keledek. Just like Xendros, he uses the smugglers to get access to magic items, but he gains security by having a strong-ish government that protects his property.
3. Granny Nightshade. The more inner struggles Saltmarsh and Keoland have, the less they will bother her. The Brotherhood can be a good tool for her to keep the power of the others in check.
4. The Sea Princes. Although the loyalists hate them, supporting this faction will keep the smuggling operations more profitable, and the princes may also get insight in possible Keoland secret plans through the loyalists. The Brotherhood gives the princes a tool to kill their adversaries in all of Keoland.

Another option that I have thought about is Xolec. Maybe he is connected to other vampires like Strahd? Then there may be Vistani involved as messengers?

The old version of Owlbear Rodeo is open source now https://github.com/owlbear-rodeo/owlbear-rodeo-legacy but no longer supported.

The archive link that was supplied works for me?

“Third Time’s the Charm” on dmsguild.com. There are more single-player adventures there, too.