We've seen a few apps that add Hollywood-type FX to your videos, but here's an app that does the same for your photos.
LensFX (free with some in-app purchase options) will let you take a photo, or load one from your camera roll. You can then choose from more than 130 effects to add, like explosions, aircraft, fire and dinosaurs. Each effect can be placed in an individual layer so they can be moved, resized or rotated independently.
There are color adjustments, gradients and vignette settings. There isn't any help, but the app is pretty obvious to use. There is even a cityscape to get you started.
I tried the app with some of my landscape photos, adding a rampaging reptile and an attack helicopter. I also placed some missiles with a smoke trail over some familiar landmarks. The effects are of very high quality, and the dinosaurs cast a realistic shadow. You re-size by pinching or expanding two fingers on your screen, and there are options to flip the image.