ToME: the Tales of Maj'Eyal

I haven't played much w/ the Shadowblade until today.

Just got Invisibility for the first time. Put in one pt and gave
it a test drive. Every thing could see me and fairly reliably
target me. Could some one explain how this skill works. I had
Invisbility 16, the undead in DF mostly had See Invisible 2. What
is the mechanism by which one is spotted and how is it tested. I
would think that 16 would match up well against 2, but it was
nothing like.

Also, tried Shadow Veil for the first time. One pt. Gave it a
couple of tests. All in DF. First one w/ a vault. Left me in the
middle of it, but it gave me ideas and I still survived.

Tried again at the open of the next level, and hit three targets
one was a banshee and after the veil was over, I was Confused.
What is going on, is this the intended behavior? Are you able to
acquire effects during the SV run but they don't effect you until
its over? Or is this a bug? I have the log if this is a bug.

Could Confuse landed right after SV ended?
What Invisibility? Maybe Stealth?
Stealth work in a way it gives you powerful evasion, I can guess it reliable if it more than 20 than targets "see stealth" just as in case of power vs saves. Also enemies doesn't tell their friends about you which is huge, and they can use abilities and spells on wrong tile.
It's a powerful thing.