Play on a monster. Your opponent can only block monsters affected by this die until each such monster with this die has been assigned two blockers.
The wording on this is a little jumbled.
Is this saying that with this die attached to a character my opponent must use 2 blockers instead of 1 or it goes unblocked? Essentially becoming like she hulk where it must be blocked by two?
Not quite. If you don't double block, you can't block anyone else.
And if you have multiple characters with Rings attached, they all have to be double blocked or you can't block anyone else.
You can still single block it, and it will be blocked, but no one else will be.