Select an area using the Rectangular Marquee Tool.
03
Copy (Press CTRL+C) the selection and paste (CTRL+V) into a new layer. Rename that layer to TENTACLE_001 or any name you like.
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Load Selection. Press CTRL and click the New Layer on the Layers Window.
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Use the Linear Gradient Tool to come up with an effect like this. The foreground is lighter than the background color.
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Make the lower part of TENTACLE_001 appear narrower than the upper part.
Edit»Transform » Perspective.
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Now make it thinner, scale down the width of TENTACLE_001.
Edit » Transform » Scale.
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Now let us go to the 'main weapon':
Filter » Distort » Shear and play with the line settings.
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With some help of Emboss and Beveling (Layer menu » Layer Style » Bevel and Emboss...), a gradient background (Gradient Tool) and another duplicate tentacle layer flipped horizontally (Edit » Transform » Flip Horizontally), scaled (Edit » Transform » Scale) and distorted... this image was produced.