Tecna's biggest mistake

[spiderbraids]

Classic quote from Winx 2x18...

Bloom: You shouldn't be so hard on yourself. Guessing the Codex was in Cloud Tower's heart was a guess.
Tecna: I made a ridiculously illogical leap in reason--I 'assumed'! (with emphasis on "assumed", so as to also say, "And unlike you, I don't make assumptions" at the same time)
Bloom: We all make mistakes, Tecna.
Tecna: Not me! I don't!

Of course, I know a few fans who would disagree with Tecna... although I will defend her that she doesn't make as many mistakes as the others.

So anyways, what would you say was Tecna's biggest mistake? Off the top of my head:

1. Assuming that Avalon could not be evil once FG told her that her logic was flawed
2. Guessing where the Codex was (it's a very distant 2nd, though)
3. Saying that she doesn't make mistakes, natch
4. Her attack on Avalon (it's a big gap between 3 and 4 though since she was proven right about Avalon later)

You know, I REALLY can't come up with any more Tecna mistakes... maybe she has a point?