if an enemy team buys vandals, buy light armor. it takes the same amount of body shots and headshots to kill you and it saves 600 creds. if they buy phantoms, keep buying heavy armor as it prevents you from getting one tapped by a phantom.
the half shield strat works pretty well if you do it randomly- once they do it no team is gonna buy vandals against them if they prefer phantom>vandal- it is the easiest strat to counter so if fnatic do it, furia should be able to counter it well 100%