Short question: does one need line of sight for actions like Vade Retro, Curing, Be Water Dude, Supression Fire...? For some one intuitively say that is needed but not for all.
You will note that the great majority of Actions and Effects of Tactics have a range of and do require LoS. Please correct me if I am mistaken but I think there is only one thing in the CoreSet that does not require LoS and that is Hexxer's character specific Tactic "Access Denied," which quite frankly is not often chosen by the player with Hexxer. Its range is 1-3. One of the things that excited this community about a year ago when SoF arrived was Laxmee whose actions do not require LoS as 0-5 and her powerful card of 4-Kaleidoscope which has range 1-7.