Creating a Fortress that Allows Owner to Scry, but Blocks Others

I’m a GM designing the remote fortress of an ancient-but-still-living archmage (>=20th level?). The archmage lives in society at present, and only returns to his fortress a few times per year, or as needed, via a permanent teleportation circle.

Previously, the archmage hid in this fortress for centuries to escape persecution from…well…pretty much everyone, so the fortress needs to be protected against even high-level divination magic. For this reason, I plan to line the fortress with a layer of lead and have some permanent spells like Mage’s Private Sanctum, Nondetection, and similar, to prevent most/all divination magic.

At the same time, because the archmage has begun living in society again (in disguise), it makes sense that he would place some kind of alarm that would warn him, even at great distances, of intruders. Furthermore, it makes sense that he’d have a sort of permanent scrying system set up so that he alone could observe what’s going on in his fortress.

(Note: The archmage’s INT score is way above my own, so I figured I’d do the best I can by crowdsourcing…)

My Question

  • Is there any rules-as-written avenue for the archmage to simultaneously prevent others from successfully using divination spells on his fortress but also permit divination spells of his own?
    • If so, how could that be done?
    • If not, what might be the closest thing to it?

What are some items that the Artificers Magic Item Savant feature allows them to attune to or use?

The Artificer’s Magic Item Savant feature states:

[…] You ignore all class, race,┬áspell, and level requirements on attuning to or using magic items.

Class and race requirements are relatively intuitive and since an Artificer would already be able to cast spells they can already attune to items that require you to be a spellcaster. But what about using a spell scroll for a spell that is not on their spell list? Additionally, are there examples of items with spell and level requirements that an Artificer otherwise couldn’t attune to?

Is there a feat that allows a player to true polymorph at will, if not would it be balenced?

I have a shardmind fighter in a 5e game that can half way polymorph himself into objects without taking their stats,and is made of crystals, like a stick or a spear etc. It is not a 5e race so we discussed this ability. Now, he wishes for a feat where he can “true polymorph”. I think its not a bad idea but, i need to know if there’s a feat like this already, and if not and we homebrew it, how could we balance it out.

Are there effects where holding your breath allows you to avoid them?

As suggested by one of the answers to this question on holding breath, there can be situations where damage may be able to be avoided by holding your breath.

A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum of 30 seconds).

When a creature runs out of breath or is choking, it can survive for a number of rounds equal to its Constitution modifier (minimum of 1 round). At the start of its next turn, it drops to 0 hit points and is dying, and it can’t regain hit points or be stabilized until it can breathe again.

Consider cloudkill:

When a creature enters the spell’s area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 5d8 poison damage on a failed save, or half as much damage on a successful one. Creatures are affected even if they hold their breath or don’t need to breathe.

And stinking cloud:

Each creature that is completely within the cloud at the start of its turn must make a Constitution saving throw against poison. On a failed save, the creature spends its action that turn retching and reeling. Creatures that don’t need to breathe or are immune to poison automatically succeed on this saving throw.

The wording is a little confusing, does holding your breath count as not needing to breathe for purposes of potentially avoiding damage? What are the situations where holding your breath will allow you to avoid taking damage for the duration of your ability to hold your breath?

How would I design a magic item which allows the wielder to use the cantrip message?

I’m playing as a currently 4th level wizard with the cantrip “message”. In pretty much any situation where any of the other party members go ahead alone, to scout or the like, or in situations where being quiet is necessary, I always tell the DM that I’m pinging the other party members with message once each minute to check in on them. While I’m certain this is allowed RAW, it feels a little bit cheesy, and I’d like to craft a magic item which allows the other party members to cast message by themselves during our next downtime.

How would you go about designing this, using the rules from Xanathar’s and the DMG, and whatever other homebrew rules you like? What rarity would it be? How much would it cost to craft? Ideally it would not require attunement, and would not be very limited in uses. Seeing as this just replicates an ability I already have, I don’t imagine the DM would take much issue with it, as long as the costs are reasonable.

What does the Gentle Repose spell do that allows Raise Dead-type spells to work later?

I got into an odd debate and now Im wondering exactly how gentle repose is supposed to work in game.

So it started when I asked if gentle repose would increase the length of time it was possible to create a soul gem for the purpose of the soul-powered magic feat.

They ruled that no, gentle repose does nothing as it makes no mention of keeping the soul around and that in the magic rules about bringing back the dead state that when a living creature dies, its soul departs. So I went looking into raise dead and breath of life to see how they differed. I was surprised that both were conjuration(healing). I was expecting that breath of life would make some mention to the soul still being around which was why it had a limited time frame in which it could work. No such luck.

So it got me wondering what gentle repose does thats different from make whole (assuming that the dead do count as objects), repair undead, and restore corpse, except of course that gentle repose specifically states it prolongs the timeframe in which raise dead type spells work.

But why and how? I originally assumed it kept the body fresh and the spirit near, but the condition of the body doesnt seem to matter much as long as its present and mostly intact.

I had asked a question about if gentle repose worked to prolong breath of life being usable. The only answer didnt really solve it.

How to organise a multi-select list that allows for selection of both users and groups, where users can have multiple groups?

So at present, the system I’m developing has a multi-select list that categorises users by their group. For example, the select list options looked like this:

  • Administrators
    • John Smith
    • Jane Smith
  • Finance Team
    • Jordan Smith
    • Jeremiah Smith
    • Joe Smith

And the selected options allowed for a whole category as well as individual users, such as: “Administrators”, “Jordan Smith”, “Joe Smith”.

The problem is, the system has now evolved so that users can have multiple groups. So rather than just being a member of Administrators or Finance Team, they could be a member of both.

The select list needs to still allow for the selection of both individual users and whole groups. I could replicate the individual users across multiple groups, so that they appear twice in the list, but then I’m concerned it will confuse the end-user as if they use the typeahead, the user will appear multiple times under different categories.