ddd well for mine it's just my Kanye Elephant avi but I pasted in a witch hat, cauldron, crystal ball and the

smiley in Photoshop. For some simple effects you can try using
LunaPic. Upload a photo (gifs are allowed) and you can use effects like Blood Rain, Scary/Horror, Jittery Blur, etc. I forgot how you can do an easy inverted effect like Superpower's avi has but that's a good one to make the person in your avatar look ghost-like.