Use a cipher identifier to identify it as a rail fence cipher!

IOBTSHIASKLENJOCMEUAGTGLTNTUYUIIOTEALHVAPOYALWEADNOSMSAYOISORLGSHSADHUSSRBTNRSEOHONEYERVYFIONO
becomes
ITSNOTRUBYBUTITISONTHERAILSHAVEASPOOKYHALLOWEENANDENJOYSOMESCARYMOVIESYOURFLAGISGHOSTANDGHOULS

flag{ghostandghoulss}