ism
The suffix -ly could be used with the word peaceful to create peacefully.
both
ness
-ation
ment
ment
ness
-ist for A+LS reading -prefixes and suffixes
One possible suffix that could be used for the word "encamp" is "-ment", forming the word "encampment."
A suffix for "constant" could be "-ness" to form "constancy." This suffix is used to indicate a state or quality of being constant.
The suffix "leg" means to choose or to gather. It is frequently used in words related to law and legal matters, such as "legislation" or "legatee."
Economy doesn't have a suffix. You could add the suffix -ist to it to get "economist," an expert in economics.