How do you start sire without shadow spells? Leagues

How do you actually start the fight without shadow spells? I have Morytania and Kandarin unlocked and I'm a thorn mage. Every guide I looked at says use a shadow spell, stun him, or deal 75 damage. But with every weapon I use, the sire just says "takes no interest in you". I've tried lithic sceptre, trident of the seas, msb w/ addy arrow, halberd, stun spell. I'm pretty sure I don't have access to a stun weapon but maybe my game knowledge is lacking. I also didn't take grimoire so i cant swap books.

What am i missing? The task is unlocked so clearly i should be able to start the fight.