|"Yeah, I got the phylactery.|
Also, the eyes of minute seeing"
The item is utilized by burning a scroll and placing the ash into the box, which must them be sealed shut with wax and a seal depicting either a deity or a pentagram. Once this is done and the item is worn, the phylactery imparts knowledge of whatever was on the scroll to the wearer, although language differences may preclude understanding, but only for as long as the phylactery is worn.
While this has many educational and ritual applications, the most interesting possibility for adventurers is likely to be the ability to store spell knowledge from spell scrolls.
The boxes vary in size and can hold 3d6 spell levels. The scroll or scrolls to be stored must be burned until no text is visible and then quickly (within one turn) sealed into the phylactery. If the user is in a hurry then the DM may want to require a Dex test of some sort.
Note that magical scrolls can not be cut up to fit without ruining their magic, and that a scroll from which some spells have already been removed by use is no smaller than it was when new.
For example, a box is found and identified for what it is, although the capacity is unknown to the finder (perhaps "small, medium, or large" could be given as a hint by the DM). A magic user finds a scroll of four third-level spells and casts one while on an adventure; this scroll still counts as 12 levels for the purposes of using the phylactery even though it will only confer the knowledge of the three remaining spells to its user. If the box only holds 11 or less levels, then the first the magic user will know about it is when there is some ash left over and the scroll is ruined.
Protection and other non-spell magic scrolls can be converted to "spell-level equivalents" by dividing their xp value by 200 and rounding up. Thus, a scroll of protection from lycanthropes is equivalent to 5 spell levels and one of protection against demons to 13.
The phylactery does not grant any more uses of magical effects on the wearer than the original scroll does, it merely allows quick and convenient access. Thus, a scroll of three fireball spells still only allows three fireball spells to be cast (at which point the ash of that scroll will be useless) and a scroll of protection can be called on but once.
When storing non-magical information the DM must make a judgement about capacity but a treasure map might be, say, three spell-levels worth, and a speech or ritual one spell level equivalent per round. It is possible to mix magical and non-magical text but doing so would make it impossible to "recharge" the magical texts as there would be no way of removing only the expended scrolls and leave the other material behind (the UA gather cantrip is not sophisticated enough for this task).
Note that there are many non-magical uses for such a phylactery. For example, a path through a labyrinth may be placed inside and given to someone who is to be allowed access. When the person leaves, the phylactery is removed and unless they have made some alternative effort to record the path, the knowledge is lost. Pass-phrases, special rituals, and many other things may be usefully imparted on a short-term basis by the use of this item. However, it does not grant spell-casting ability to those who do not have it (including high-level thieves who may not use this item to cast scroll spells) although spell-casters may risk casting spells higher than their normal limit as per usual and, similarly, spells must be of the correct class for the caster (DMG p128).
No more than two boxes may be used at one time and any given scroll must be placed entirely into a single box; putting a part of a scroll into one box and part into another (or simply discarding it) will negate the use of the entire scroll).
Also notice that successful use of this item requires various tools: something to burn the scroll with and in, which can catch the ash; some way of transferring all (ie, 99%) the ash into the box; sealing wax and a metal seal with one of the required devices upon it; and the scrolls themselves of course.
|"So, that's 'under the gate,|
over the narrow bridge,
through the enchanted hedge,