After 15+ years of gaming, someone finally bought a set of Dimensional Shackles. After looking in the PHB, and at the item description I could find nothing as to what adverse effects manacles actually had on someone (aside from these particular ones barring extradimensional travel).
So, I'm asking if anyone knows any specifics as to what disadvantages you have when you're shackled with manacles. I've speculated with the DM for this particular campaign, but he won't lend me anything beyond speculation. I checked with wizards in an email, and they basically sent back a wordy "We're not sure; we've never had the issue before."
I spent some time in email tag with the other gamers in my crew to figure out what we want from manacles, and what doesn't need to be there.
My latest catch-all idea is to emulate what rifts did with a particular set of manacles. They created a special type of armor for spellcasters, that would purposefully inhibit their ability to cast spells... welded joints, concrete mittens, and a mouthbar. I'm notgetting into all that, but it brought up a good point. Why don't we just consider manacles to be a special type of armor?
It would have a max Dex which limits reflex saves, spell failure percentage, and armor check penalties. Of course the amount of penalties would change based on how severe the manacles are: like handcuff manacles (wrist to wrist) are much more severe in penalties than wrist to chain to wrist. And similarly with leg irons as part of the 'armor' would make the penalties more severe.
Any help fleshing out an answer would really help me out.