Kalendraf
Explorer
Mephits (CR3) can be challenging to a low-level party. Their DR 5/magic can make them somewhat challenging to parties w/o access to any magical weapons. However, they have fairly low damage from their attacks and their breath weapons tend to be more humorous than harmful.
If you want to make them a bit tougher, you can consider adding hit dice. The MM lists them as ranging up to 9HD. They'll get a size bump along the way, which will increase strength as well as give them a bigger die type for their attacks. It will also improve their saves, hit points, skill points and extra feats. The breath weapon will also improve somewhat as will its save DC. I'd consider this as an option if you're having trouble finding what you are looking for in Para/Demi/Quasi/Semi-elementals.
If you want to make them a bit tougher, you can consider adding hit dice. The MM lists them as ranging up to 9HD. They'll get a size bump along the way, which will increase strength as well as give them a bigger die type for their attacks. It will also improve their saves, hit points, skill points and extra feats. The breath weapon will also improve somewhat as will its save DC. I'd consider this as an option if you're having trouble finding what you are looking for in Para/Demi/Quasi/Semi-elementals.