Scars of Time

As an additional cost to cast this spell, tap an untapped Musician you control. You may remove any number of verse counters from creatures you control. For each five counters removed this way, take an extra turn after this one. During each additional turn's end step, put a -1/-1 counter on each creature you control.
What was the start of all this? When did the cogs of fate begin to turn? Perhaps it is impossible to grasp that anwer now, From deep within the flow of time...