Syrannis' Mystic Sheen is a cloak with resistances to all schools of magic.
This cloak is nice for a starter resist gear the downside is the lack of stamina which most resist gears have. A ring with similar stats called Band of Many Prisms drops from Omor the Unscarred in the Hellfire Ramparts on Heroic mode.
If you are planning to use this cloak in the future it is adviseable to have it enchanted with some more resistance depending on where do you plan to use it
- Enchant Cloak - Major Resistance is the best all around but also a very costly enchant upping the all resist to 19.
- Enchant Cloak - Greater Resistance a much cheaper alternative which ups all resistance to 17 just 2 less than the above one.
However for most fights all resist is a bit of an overkill and generally just 1 type is required you could settle to have just 1 type of resistance enchanted for fights you are visiting often.
An interesting side note that in the item's name the game creators misstyped the name of Commander Sarannis to Syrannis