@Josh103  
I agree it was ingenious on the meta-level. With Discord being perfectly content with being Chaotic Neutral, and also knowing how dumb and predictable Tirek was, he could lead Tirek into thinking tricking Discord was HIS idea, when in actuality he was just leading Tirek on. Discord wasn’t exactly being subtle about it, what with Discord telling Tirek his motivations and even putting on an angel halo when Tirek thought he was getting close.
 
Discord gave him the bait Tirek was looking for, and Tirek fell for it hook, line and sinker. Villains are incredibly predictable to beings of chaos afterall. Discord never claimed to be a villain himself, he’s a trickster.
 
Of course, what Tirek DIDN’T KNOW was that Discord gave huge hints to the Mane 6 BEFORE he talked to Tirek on how to unlock the power to stop Tirek. He didn’t even tell him this AFTER Discord supposedly ‘trusted him completely’ Plus there’s the fact he was ‘supposedly’ going to stop Tirek for no real reason in the first place. Afterall, Celestia can’t ‘send’ Discord to do anything. Not unless he finds it fun.
 
But Discord loves to play puppet, and without a bit of risk he finds it boring. To just capture Tirek in his weakened state would be incredibly boring, and not his style. But to have free reign to cause mayhem alongside Tirek, get his powers absorbed by him,… only to be responsible for bringing his downfall from the getgo? As it showed at the end, Celestia was perfectly happy with Discord’s actions, so long as Twilight could play solo hero again.
 
The only thing Discord didn’t seem to be aware of when he was by himself, was the dramatic amount of magic transferred to Twilight. Personally, I don’t think Discord knew Celestia had enough power to make Twilight as powerful as Tirek even after he absorbed his own powers.
 
I mean its not like Discord gave the Mane 6 the hints they needed for the box by accident.

@CronoM  
It was ingenious actually, at least at a meta-level. I don’t have the dedication to type out why. Mostly the fact that it was true that Tirek said, Discord HAD really gone soft, and Discord himself certainly took note.

@Josh103  
I’d like to believe that, but nothing he ever said or did was even remotely methodical or ingenious.
 
Tirek’s ‘evil convincing’ was not only predictable, it was practically handed to him. If Discord didn’t intentionally drop his motivations, Fluttershy’s name or wear an angel halo for comedic(baiting?) effect, Tirek would of had nothing to work with. Tirek also assumed Discord knew nothing of his past, otherwise his ‘gift’ would of been a red flag.
 
Considering how smart we know Discord is in prior episodes, and also comparing the same scenario in Aladdin’s episode, “When Chaos comes Calling”, with Chaos and Mirage, Tirek’s attempts at deception seem rather pathetic, and the idea that they worked would take a miracle. And Discord’s even a bit smarter then Chaos, so it really doesn’t make much sense.
 
If Discord wasn’t busy literally GIVING Tirek a ‘turn back to the dark side’ speech, normally Discord would be drawing a face puppet on his hand and mimicking Tirek’s entire speech as he said it.

@CronoM  
I think it definitely shows that Tirek is more intelligent than he seems.
 
He just likes to use brute force more. A lot more.

Is it just me, or is ‘first scene’ Tirek (or G1 Tirek) INFINITELY more intimidating then Lord Tirek for the rest of the two-parter?
 
I mean look at this guy. This guy is terrifying. Definitely above ‘Bowser’-level intimidating.

“Go fourth, and conquer in the name of your sire, Sunny One!”  
“Nuuuuuuu!”