PvP battle; player vs. player
Used in video games to describe combat between human players, as opposed to fighting AI-controlled enemies.
This game's main content is PvP battles.
In PvP, reading your opponent's moves becomes important.
Compound of 対人 (たいじん, 'facing a person') + 戦 (せん, 'battle'). A straightforward modern coinage from gaming culture.