Complex sentence: Blue Whale is described as being based on the relationship between participants (or challengers) and administrators, involving a series of duties given by the administrators that players must complete, usually one per day, some of which involve self-mutilation.
Split into simpler sentences: Blue Whale is described as being based on the relationship between participants (or challengers) and administrators. The administrators prescribe a series of duties that players must complete, usually one per day, some of which involve self-mutilation.