The Treacherous Sphere Staff is a sentry summon weapon dropped by the Treacherous Conjurer. It summons a Treacherous Sphere that shoots energy bolts at nearby enemies and can goes through walls.
The best modifier is Ruthless. The Mythical modifier provides the widest array of stats bonuses, but these primarily affect the initial summon rather than the resulting minion. Additionally, Minions cannot deal critical hits. The only significant advantage a Mythical Treacherous Sphere Staff has over a Ruthless one is knockback.