I'm playing a level 4 Svirfneblin wizard with the following statistics matrix: 6, 16, 17, 19, 13, 7. I'm debating my choice of 4th level feat (I think I want a +1 to Int and then I'm getting Resilient (Con) next in 8). That means that my options are Linguist, Keen Mind, Observant and Fade Away.
I'm interested in Fade Away: does the Invisibility that it grants require concentration or to use it, would it eliminate some spell that I am currently concentrating on?
The wording does not specifically say that become invisible, you do not to emit the invisibility spell out). I'm not sure how it works, and I can not find the answer online. How does it work?