Flukemon

Attacks
They patrol around. Then charging at the player, dealing damage on contact.

Once this enemy dies it's two body parts will reanimate. Both of them attacking the player.

The top half hovers above the player and doesn't do much else.

The bottom half will crawl quickly towards the player, even over walls.

Tactics
You will likely dispatch this enemy quickly. The more troublesome part is the creatures that come after it. The top one will reanimate first and hover above the player. You should dispatch this one as quickly as possible before the ground dwelling half comes back.

Once the ground dwelling half comes back it will charge the player. It is able to crawl up walls as well so it can chase the player almost anywhere. You will have to dispatch this thing swiftly with your sword.