The Freedom of Movement spell cast by this item is cast at caster level 55.
When wearing this ring you are immune to being Forcecaged by item or special ability. When wearing this ring you are immune to being grabbed by spell, item or scripted ability. When wearing this ring you are immune to being Mazed by spell, item or scripted ability. When wearing this ring you are immune to any movement speed decrease by spell, item or scripted ability.
Use Freedom of Movement (7) x4 a day
(Situationally useful and giving up a ring slot is always a concern for most toons)
Seems decent to me, my playstyle/toons probably wouldn't get much use out of it (take what I say with a grain of salt for this reason), but I can definitely see it being used as a 'high skill' quick swap-in item to bait various abilities, and it doesn't look imbalanced for this purpose.
Would agree that Level 59 FoM is more appropriate for a Paragon item, and I also don't think the FoM should be lost when the item is swapped out (for the reasons explained above).
The current version might even be a little bit too niche, could possibly add some extras to increase utility of the item.
Possibilities include (not all of these necessarily need to be on the item at once): *Spell Immunity: Entangle - for Kuo-Toa Webs, as Matt said *Immunity to Arachill webs - like the base item KE linked *Spell Immunity: Flesh to Stone - potentially overpowered, but it may be appropriate considering it's a Paragon item with no immunity %