I would sit him down for a few minutes- attempt to be as brief as you can, and get straight to the point by explaining what I believe he did wrong from my perspective. I'd go over how metagaming like he did only led to the deaths of half the party, and what kind of impact his kind of "no no one's dead, I'm altering this play-reality with my Mind!" sentiments destroy the gametable dynamic.
I would then offer him this choice:
"You can either accept my rulings as final and accord me with the respect I give you, or you can leave the group."
And for a flourishing close, I'd say "I won't give you that choice twice."
This might sound a little less than knee-jerk, and hardly confrontational / big boss like, but frankly that's not necessarily your job as DM. The players play of their own free will, coming and going as they please- the only power as big boss is that which they give you, and acting all puffy chested leader boss when he obviously isn't considering you in this context will lead to little good. Beyond that, giving people choices, even if they are ultimatums, is an almost infinitely better thing to do than simply say "Get out."
I would then offer him this choice:
"You can either accept my rulings as final and accord me with the respect I give you, or you can leave the group."
And for a flourishing close, I'd say "I won't give you that choice twice."
This might sound a little less than knee-jerk, and hardly confrontational / big boss like, but frankly that's not necessarily your job as DM. The players play of their own free will, coming and going as they please- the only power as big boss is that which they give you, and acting all puffy chested leader boss when he obviously isn't considering you in this context will lead to little good. Beyond that, giving people choices, even if they are ultimatums, is an almost infinitely better thing to do than simply say "Get out."