Protection from everything sounds about right for a format where deadly combos appear like mushrooms after rain.
Having one such coffin in your 99 would never hurt, and taking into account that it's colorless, makes it playable in almost every single archetype.
There are two decks, however, that would love The Stasis Coffin more than others: Grixis Artifacts with Mishra, Eminent One commander, and Azorius Artifacts with Urza, Lord Protector.
That's all for the best 15 cards in MtG's The Brothers' War set. In addition to this list of the best The Brothers' War cards for commander, be sure to check out our other MtG guides and card lists here.