Hello,
Are you using a shield (required) and are you within 5 feet of a companion ?
If so, attacks against that ally should be at a Disadvantage (the way it is written/described in the game anyhow)
[i.e. on the tabletop, it is a Reaction and should work only once per turn].
Oh, wait, it is most probably a Reaction !
So check your available Reactions on the right-side of the UI. If it works, it is rather an excellent choice!
Last edited by Baraz; 09/10/20 04:07 AM.