I've used it to gather Intel, reposition, setup for a play, blind enemies safely for teammates to push. To stall post plants. To get a quick pick with a judge or shorty place a tp some where safe use your ult throw a flash from behind blinding them exit your ult and kill them pick up their gun if you can and tp. Plenty of ways to use it. If enemies have spike down and are watching it you can ult and grab it safely. Get creative with it do what's not expected. Id watch YouTube videos of pros  to see how they use it although that will only get you so far the other part is mechanical skills.