Cast Storm Herd by paying ({8} magic symbol) ({W} magic symbol) ({W} magic symbol) , creating a number of 1/1 Pegasus creature tokens equal to your life total.
Cast Semester's End by paying ({3} magic symbol) ({W} magic symbol) , targeting every creature you control.
Venerated Rotpriest triggers for each creature targeted by Semester's End.
Resolve the first trigger, causing an opponent to get a poison counter.
Repeat step 4 until an opponent loses the game due to having ten poison counters, then repeat for each other opponent.