Spontaneous combustion is the ability to cause things to explode or burn with one's mind. Amanda Strazzulla is the only character known to have this ability.
There seems to be no limit to the size of an object Amanda can explode as she was successfully able to combust a police car, a dog, and a tree. Initially, she was only shown to be able to use her ability when under extreme frustration or anger and had little to no control over it. The objects Amanda combusts take a few seconds to succumb to the effects of the ability as at first they only start to heat up (Boom). It's unknown if Amanda has immunity to the effects of her power.
Amanda can affect both organic and inorganic objects with this ability. Recently she has shown more control over her ability; she produced sustained pillars of fire (Slow Burn, Part 10) and short-lived jets of flame (Close to You). It should be noted that the latter example was done near Lydia and caused her no apparent harm.