I am wondering if the slang speak "hard" as in "I hard countered her champion in the last game", can be used in other sentences to mean a similar thing, and how widespread the usage is. Notice the placement also, which is derived from its slang use in the gaming community.
I hard rejected her when she asked me out.
In your example sentence "hard countered" is a phrasal verb derived from a adjective (hard) modifying a noun (counter). I would say that "I hard countered her champion" means "I used a hard counter to her champion" rather than "I countered her champion in a hard manner." In most cases when "hard" is being used as an adverb, it would not precede the verb:
I worked hard all year.
The team trains hard.
Similarly, a more natural phrasing of your second example would be:
I rejected her hard when she asked me out.
