Create a new Scene

Add an Area2D Node

Rename it to Spikes

We will detect collisions and

Trigger events when collisions occur

Add a Sprite and use the tile_0068.png 

as the texture.

Add a CollisionShape2D node and set the shape to RectangleShape2D

Resize the collision shape to fit the spikes

Scripting the Spikes

Add a new script to the spikes node

Connect the body_entered signal.

Check if the colliding body is the Player

Call the game_over function

The functionaly for the spikes is the same as the enemy

Now you add Spikes to the level to challenge the player