mergewalls VS foundryvtt-magic-items

mergewalls - A module to reduce the number of walls in your map by merging those that have common points and are in the same line. When loaded a recycle icon is added to the walls button list, which when pressed will merge walls. It can take some time for complex maps - so be patient and wait for the UI notification that it has finished.

Merge Walls

FoundryVTT Magic Items - This module for Foundry VTT and specific for the DnD5e system, adds the ability to create magical items with spells or feats that belong to the item itself, such as staffs or magic wands, which will be automatically inherited from the character who owns the item.

Magic Items - Allows adding additional spells and such onto magic items directly. Very useful for items that function on charge systems that can be upcast, though a little tricky to work with.

Well there's your problem right there.

Magic Items might help you. I believe you can set it to use multiple charges and scale with number of charges.

a solution could be to code your cutom "feature" into custom magic spells and use the mod "magic items" which let you add spells to magic items with customizable charge cost per spell, number of charges, charges regained at x and so on

What you want is the Magic Items Module... it works with MIDI-QOL and DAE. https://gitlab.com/riccisi/foundryvtt-magic-items

Magic Items

There's an issue for this raised on the module's gitlab page: https://gitlab.com/riccisi/foundryvtt-magic-items/-/issues/82