Kill the one in the center and bam, no more ritual, can it get more difficult please

agreed

they also stop the ritual if you even get close because they're AI to attack you overrides they're intention to complete the ritual

maybe add some sort of magical defense while casting a ritual that can only be breached by potions and prevents them from stopping the ritual to chase you for particle affects I was thinking a thin shroud of darkness

Could make it so that in order to stop the ritual, you must manually take down the "worshippers" first before the main ritualist can even be damaged, and yes, even without the worshippers, the ritual is still going, making the players hurriy if they wnt to stop the ritual by killing the main ritualist.

When damaged, worshippers will fight back, making it much harder to stop the ritual now.