Armifer in March requested our opinion on what types of barrier spells we would like, and listed among other things potent barrier spells like Sheer, with serious restrictions. Meraud's Mirror is proposed with that in mind.
Meraud's Mirror creates an invisible barrier of holy energy surrounding the cleric that will reflect back onto the caster any non-TM spells. The each attack weakens the barrier, until it breaks and no longer will reflect the spells. However, due to the unstable nature of the holy energy surrounding the cleric, the cleric is unable to cast Harm Evil or Harm Horde while the spell is in effect.
So there we have it, a powerful Sheer like barrier, with a negative response to the caster, with serious drawbacks- in this case the inability of the cleric to cast our two most powerful TM/DFA spells- Harm Evil and Harm Horde, and the spell provides no protection versus TM.
"militantly enforcing the overly rigid standards of you and your small collection of friends"