Thanks for the help! I managed to get the script to compile and run correctly after adding that casting bit and a few other alterations to the script.

My original intention was to get the player to cast the Shout skill on himself so I made it like this.

Code
IF
ObjectFlagSet("QuestUpdate_BurningPast_IsWerewolf", (CHARACTERGUID)_Player, _)
THEN
CharacterUseSkill(_Player, "Shout_PolymorphIntoWerewolf", _Player);


That part on handling NPCs casting spells on the player would come in handy in some future dialogues for sure.

Greatly appreciate the help LaughingLeader!