Alba's Fog Cloud

This enchantment enters with 2 concentration counters on it. If you control a wizard, this enters with 4 concentration counters instead.
At the beginning of your upkeep, remove a concentration counter from this enchantment.
Rogues you control get +1/+0, shroud, and can't be blocked. (A player or permanent with shroud can't be the target of spells or abilities.)
At the beginning of your upkeep, if there are no concentration counters on this enchantment, sacrifice it and scry 2.