Orca creates swirls on your dragon and may appear one of two ways. It can modify one marking to make it look swirled. Alternatively, it creates a simple marking that adds a patch of color from the elemental color scheme, or white, to the lower spine of your dragon (always close to the hindlimbs or where hindlimbs would be). It can take on some pretty weird shapes along with some plain ones–look at real orca markings for some ideas! The edge will appear soft, but not fully blended. If a marking is multiple layers, you may choose to affect the whole mark or just some of the layers.
Here are examples of orca affecting blanket and striped:
Charged Orca
Charged Orca may create a swirled marking anywhere on the dragon. Additionally, it can cover up to 1/3rd of the dragon, rather than a small back area.