Black mass
This skill can only be used once a year and only during same
time that nuns are keeping prayer.

Using this skill will give every priest in room evil
manifestation (undead,slaad,demon etc.) and move these
horrible creatures to convents prayer room through
magical portal. These monsters have pre set spells/skills
what they can only use. Additionally user of skill is given
manifestation of some bigger mob to lead that rampaging
horde.

These monsters then need to "desecrate" room by killing
enough nuns or holding room for some time. Monsters need
to get to last room of library to complete their devastation.

Nuns can use services of abigail for raises, prots & such.