Invisibility Ring is a Universal Item to be introduced in Tools of Hero Kind.
Rulings[]
For as long as a Hero has this item at the entrance of your dungeon or in your dungeon, you cannot play spells, even if you not the active player. However, you can play Items and Room abilities.
Since the Boss ability is an Item, it cannot be Counterspelled.
The Boss ability allows you to cancel a Spell played during your portion of the Adventure Phase (when you are the active player).
Trivia[]
This card was first showcased at the end of the Strategy Guide as a teaser to Tools of Hero Kind .
Possible reference to Gollum and Bilbo Baggins from the Hobbit.