Effect updates and description changes can be seen here.
Strafe is a Justice deck exclusive effect card. For 4G, it deals 2 damage to all enemy monsters, acting like an upgraded version of Shootout. It also works like a weaker, all enemy version of Punishment, much like Perseverance's Worsening and Pollutant Gas, but since Beta 35.0, it doesn't have a secondary effect that makes it stronger if you have less HP than the opponent.
The effect can be used with Asgore to kill all enemy monsters just for 18 gold, it can also be used with Papyrus or other Charge monsters to kill the monsters that didn't die. This is also good with Undyne or Undyne's Spears to kill out the remaining monsters.