ok i get that she was able to get inside rebekah's head, (maybe finn showed her how) or as she said that she needs to be relaxed or whatevr i get that

but damon drinks vervain every day,so he would get used to it,and to prevent the originals to enter his head so how was sage able to see what's in his head??

Damon already do that to Stefan in Season 1 and Katherine to Stefan in Season 2, but was the other way around... thay put thoughts in his head... the dreams!!

Vervain it's just for the complelling...

yes but at the time both damonj & stefan weren't on vervain remeber in S2 when damon gave katherine vervain so klaus won't be able to comple her.

elena also wear the neclace with vervain so vampires and even orginal vampires can't cople her

Weird :/ And I remind that she didn't see Elena here ;/

Damon did it to Stefan, and Katherine to Stefan, too. Stronger vampire's can get into the minds of weaker vampires, just as vampire's can put dreams and that kind of stuff in humand minds.
It's just something TVD hasn't done in a while =)

yes but at the time both damonj & stefan weren't on vervain remeber in S2 when damon gave katherine vervain so klaus won't be able to comple her.

elena also wear the neclace with vervain so vampires and even orginal vampires can't cople her

The only thing I didn't like was when Sage kissed Damon just to show him Rebeka's memories/plans. That really angered me because she could've done it a different way. I don't think it really meant anything though as well as the kiss with Rebeka, he only kissed her because he had a plan. He loves Elena period

What kind of power does she have to be able to do that? I don't get it. I would like it explained.