You could use the bullet behavior:
+PlayerSword collides with Enemy:
---Enemy:Bullet:Set speed: 400
---Enemy:Bullet:Set angle of motion: angle(player.X,player.Y,self.X,self.Y)
---wait 1/4 seconds
---Enemy:Bullet:Set speed: 0
If the enemies move with some other behavior then stop it's motion, disable it, move with the bullet behavior then re-enable the it after the wait.
You could also use events or Custom movement like yuquanzhou007 suggested, whichever method you prefer.
This is really better than custom movement, thank you!