The only way not to get resisted and works 100% of the time is to get up
real close.

This is my usual tactic at lvl19:
Cast Quickness on tank
Get up REAL close to the enemy (aviak in my case)
Cast Tashan
Then Languid Pace
Then Disempower
Then Choke

At this point I have used 50% of my mana and can comfortly sit down and wait
for the tank to do its business and I just wait for the next one while
medding.

As a side note, with this tactic my tank friend was taking very little
damage (he is lvl20) and killing it much faster than the 2 tanks that we
were alternating kills with.

I think that with this tactic I may have been resisted 1 time only in 3
hours of play! The only side effect is that as you debuff them, they tend to
get real mad at you, hehehe! Just step back.
I do tend to forget often that I am not a tank too and melee a lot, but that
is ok as we share damage together.

Well, I am close to lvl20 now, anyone have any suggestions on what spells to
buy next?

Eregil - Erudite Enchanter - Mith Mar