This magic item cannot be discarded by an opponent, or by any card an opponent controls. (Def)
Copyrights:
TSR
Wizards of the Coast
For any player interested in making sure they can win by levels, this is one of the greatest cards ever made (completely un-fitting with the D&D magic item, but still good). Ten levels can me the world in battle. While it isn't my style (I still believe restriction powers and instant wins are the most powerful type of attachments, but I can see this making it's way into many decks.
This, attached to any cleric spellcaster, allows any deck to use the "quest" spells of the Underdark set that require high level casters. Ten levels that can not be removed by opponents (you can still sack it for something like a bag of holding or as a side product of any card you play) can often be too much for some decks to deal with.
The only other items/artifacts with this kind of power boost are The Throne of the Gods (460/4th), Axe of the Dwarvish Lords (2/AR), Hero's Chalice (9/FR-chase), and The Winner's Cape (520/4th).
I'd recommend this for any deck that has multiple spells that are based on casting champions level or any raw battle deck.