Eh, I guess overall what I can't do is more of like what I've never tried to do so far since most of the things I've tried have gone right, but here's what I have yet to do properly-

Find my DreamGuide
Eat peanuts
Time Dialation
Transformation

That's really it, unless you consider perfecting things a failure since I have yet to perfect them [ohh, repetition] that'd include teleporting and summoning people.