I don't think you have any defence against Vine Shield. I think that it casts Tangle Vines on the attacker... but don't know for sure. Maybe I should try that.
The damage from repel is just a 1 point, but if 8 points of armor-piercing fire damage are given besides it as they are for normal attacks... *shudder*!
On the other hand... I could see need for pike-wielding sacred unit.