Basic idea:
On Hit condition - EnemyObject move at angle angle(player.x,player.y,enemy.x,enemy.y) distance
"angle(player.x,player.y,enemy.x,enemy.y)" gives you the angle between the player and enemy
This results in the enemy sort of teleporting away from the player when it gets hit. For smoother motion over time, you'll want to use a bullet behavior on the enemy - set the angle away from the player with the angle expression as before, set a speed, and have that speed decay over time.