So exactly how do you get the feat of str?

Q u o t e:
ok I found some rifts around the place but im phased out when i get near them any ideas?

That is a known issue that is being looked into. Mostly this happens when the rift has already been closed but the spell and other ambient effects can see be seen from afar. This is confusing many as it looks like the mobs simply disappear when you approach.

You should still be able to find active rifts though it is a matter of timing and knowing the appropriate locations. When you have done all 4 elements you should be awarded with the feat of strength.