Proposed Mythallar Designs

The only real limitations are listed here https://www.dndbeyond.com/magic-items/2188403-ythryn-mythallar

500ft sphere moves with no mass limitations. Anything outside the sphere can still be moved with it as long as its structurally sound.

30ft per round is about 6 mph. Telepathic link to anyone attuned

Control weather up to 50 miles - must be within 30 ft of the mythallar core

Can recharge the uses of any magic item. Limit once per item per day. No limit on the number of items.

River's Proposal

A flying statium, built with stadium 'petals' resembling a flower or something idk.

Benefits
• Free Passage: Players will be able to catch a ride in moderate comfort into areas that might otherwise be difficult (closed borders, high tarrifs, dangerous terrain etc) and be welcomed as they're traveling with an interesting cultural event.
• Artistic Inspiration: Its design and construction are awe inspiring. Players start each 'travel segment' with inspiration. High volumes of foot traffic will allow players to embark easily without being noticed with a flood of travelers and tourists. City watches and guards will be on higher alert due to the presence.
• Flexible Design: Has the ability to 'land' on water, land or remain floating. Extended platforms allow for offloading or docking with vehicles on nearly any terrain.
• Protective Shell: Despite a lack of obvious weapons, heavy armor is incorporated into the design of the stadium, and the ability to close completely allows it to shrug off most damage.

Drawbacks
• Notorious: Being famous is a positive and negative. You get into places easily but everyone knows your coming and wants to see the floating stadium. Will have an actively negative impact on any kind of stealth missions. Even dropping players far away will spark talk among local villages and townsfolks which will spread after them. For non stealth things, anyone 'from out of town' seen doing illegal shit will be searched for at the stadium first.
• Small Quarters: If there is an audience on board the players will be bunking in the crew quarters.
• Civilian: The bare minimum compliment of weapons and security, just enough to protect the audience. NOT suitable for large scale assaults or ship to ship or ship to monster combat.
• Variable Storage: If the players are traveling further than one scheduled performace period, they won't be able to store large vehicles or much cargo with them when they travel and will be limited to the crew quarters.

Xior's Proposal

A base ship carrying the mythallar, crew, weapons, and some critical cargo with most of the perimiter being allocated to various modular platforms that can be used for a wide variety of missions.

Benefits
• Mission Oriented - Xior's main focus is researching zhentarim activity and hunting their bases. Often in remote locations with their own supply networks, assaulting them at any kind of scale is a dangerous endeavor. This ship is designed to be small, carrying everything needed for this or any other combat oriented task.
• Heavy Armament - The base ship will have heavy armor and several mounted and remote ballista positions by default. What would be entire combat encounters in the other versions of the mythallar module have a chance to be bypassed completely here.
• Downtime Work - With a built in teleportation circle on the deck, the ship can either embark to a location and allow for instant transport, or if a larger party needs to be moved, head out before hand and begin working on bridges, tunnels, waystops, etc. This will eliminate natural obsticles and remove difficult terrain effects while traveling on foot. (while also charging local governments for difficult infrastructure work)
• Spacious - The ship is self only takes up about 200 ft of space in one direction of the mythallars 500ft radius. Bringing it on any given assignment will allow for easy storage of a massive amount of loot, vehicles (including cottages), armaments. Whatever needs to be hauled, even if its not attached to one of the platforms
• Room for Expansion - Because the base element is so small, if something outside of the two cargo or construction platforms comes to mind, it can be built and implemented easily in downtime and utilized for each mission (maybe a gunship or research kind of thing?)
• Small Crew - Using existing artificer technology from Navia, the entire ship can be fully crewed, including weapons manned with about 4 people. Any remaining people are generally brought on for specific modules like construction or cargo workers, This means more people can be brought on board and used for assistance in missions

Drawbacks
• Utilitarian: Basic crew quarters don't provide a comfortable travel space. No benefits to long rest or affected conditions.
• Background Operator: while it makes steady progress on objectives for both the players and the company, its not very exciting and doesn't make it easy to get places outside of its teleportation circle
• Busy: If the players choose to travel onboard with it, the ship will have lots of orders to fulfill so there might be several stops before they actually end up where they need to be.
• Dangerous: This ship is designed to go to difficult areas, be that magically or naturally dangerous, its likely to encounter problems of some sort along the way and might call for assistance. Xior's missions tend to involve dangerous enemies and nasty consequences. Think Nivian Rescue Mission