@Greenjack  
I know. I just wanted to elaborate on that stuff. :)

@Amethyst_Crystal  
I know, I’m just saying that it looked less like her dicking with her student’s mind and emotions and more like her actually thinking through a competent battle plan.

@Beau Skunky  
@Greenjack
 
Keep in mind that Celestia and/or Luna were the ones that captured and imprisoned Tirek in the past as well, with the help of Scorpan’s intel.
 
Tirek has made sure that he’s become strong enough to get revenge and steal his captors’ magic… but there’s nothing to take.
 
If the sisters were smart enough to imprison this guy before, I’m sure he had a moment of fear, knowing everything wasn’t going according to his plans.
 
But then he brushes it off afterwards, taunting the royal sisters and banishing them, so certain that he has defeated all his enemies.

@Beau Skunky  
and it showed her doing something clever for once, even if it really was her handing the responsibility to twilight once again.

@Hex101  
I loved that part to. It was a very subtle, “We outsmarted you, can’t believe you thought we’d make it that easy for you” moment.

I LOVED that look on Celestia when he realized there was nothing to take.

@albert19  
It’s not honor, it’s hubris–the tendency of every villain ever to disregard that which doesn’t pose an apparent threat. Once Twilight was depowered, she was as invisible to Tirek as Mordor’s back entrance or the Death Star’s thermal exhaust port.
 
Of course, if he hadn’t been such a douchehat to Discord, maybe the latter could have warned him about the Elements, the Tree, the Mystery Box, and the ongoing danger posed by the magic of friendship(TM). But hey, hindsight’s always 20/20.

Celestia knew that Twilight had two powerful options:
 
1)Combined Alicorn Magic  
2) Rainbow Magic from Tree of Harmony
 
First one resulted in stalemate, the second one resulted in victory. :p

@albert19  
Celestia read ahead in the script and knew Tirek would be a fucking moron.

If Tirek had taken Twilights (and, by proxy everypony else’s power. Then what use would Celestia be to Tirek? Or even herself? Once Twilight had gotten herself killed off?

Celestia would have been salty as hell is Tirek didn’t have honor and killed Twilight the second he got her magic.