Crystal Guardian

Attacks
Shoots energy beams from its arms, in the direction of the player.

Calls down multiple energy beams from the sky.

Deals damage on contact.

Tactics
This is a difficult boss to defeat, mostly due to difficulty in finding a safe spot. Your best plan is to slash at the Guardian a few times and then get distance to avoid the beam from its arms. The beams from the sky have very little warning as to where they appear so, just keep moving is your best bet with those. In short slash whenever you see an opening, and move the rest of the time.