Simian Reflexes uses the phrase "an enemy you can see" to refer to enemies in the forward arc. This phrase is confusing since it sounds like "line of sight" yet is not the same thing (see: Flash Of Pain as discussed over here). I ran into another card that clashes with the phrase: Wall Of Illusion. Wall Of Illusion says "enemies may not sight through." "Sight" may mean "line of sight" only, but it sure sounds like "seeing." I put a Wall Of Illusion directly in front of a Monkey, stood on the other side of it (and therefore was invisible), and played a Stab. Lo and behold, being unable to "see" didn't matter: Simian Reflexes triggered off of my being in the forward arc. This post gave a similar situation with an invisible spellcaster, just via board layout instead of a Terrain card. All of this could be resolved by rephrasing Simian Reflexes.