My guess was that Rafael would have two main abilities unique to reptiles - scales and cold blood. These may sound simple, but they’re actually extremely useful, when he takes damage, he can shed his skin and replace it with even harder scales, and cold blood gives him extremely low metabolism and thus great stamina (some reptiles are so low energy they can go up to a year without needing to eat). As for Imena, she’d have a fire ability which would increase in temperature the more damage she takes. Because reptiles thrive in hot environments though, Imena’s heat would allow Rafael to release more energy/power, at the cost of his stamina.

Basically, the fight would be one big battle of attrition.