It's the basic of Simulation PRG. Use the terrain to keep enemy attacks from focusing on you, Conversely, let your attacks focus on one.
Basically, use the neck of the terrain such as a door.
However, be careful as the enemy may slip through your fellows and go behind!

The first two may be tough, but it is stable when divided into blocker and rear-attacker.
The rear-attacker also has the advantage of possible to safely perform Reckless action.

While exploring, you tend to spearhead, but if you advance too far you will encounter enemies in a form away from your fellows.
It takes time to prepare the formation, and the risk that the leading character will receive concentrated attacks increases.
Even if troublesome, it is safer to maintain your formation by calling your fellows step by step.
Forward step by step, it leads to a reduction in enemy appearances.

Opening a door, turning around a corner, etc., when your sight opens suddenly, many enemies often appear.
Prepare for enemy's appearance by shaping the formation before opening the door, turning around outside of the corner.

If you approach for attacking when enemy appears, the farther enemies may appear.
Approaching leads to enemy first strike, so defend and wait for the enemy to approach.

You will want to approach and attack because the enemies shooting Blast don't come close.
But doing it, farther enemies often spawn and it can be even more difficult.
In such a case, enemy will approach you if you recede once.
Hide behind a wall and hit enemies that came to the corner.
If withdrawal is not enough, you can escape with Reckless.

To summarize, "Take care your life" is fundamental.