placeholderapi_match_<PLACEHOLDER>
placeholderapi_match_essentials_flying
and the variable was true, if the player was flying the quest would progress.placeholderapi_integer_<PLACEHOLDER>
%player_level%
your quest would look like this: placeholderapi_integer_player_level
Example, if you wanted to make a quest which activates as soon as player reaches experience level 100, you can set up a quest looking like this: