Some things amiss with this sentence: “You could use a little more tact Vanore!” she muttered from under a forest-brown cloak. Four hooves balanced delicately behind the cloak, and a midnight black tail whipped irritably across her withers.

'...behind the cloak? I assume the she is a centaur. Is her cloak cut with very short? With the sides and ends falling in front? Some mention of the cut of the cloak should be given the reader.

'The withers are located at the bottom end of the neck and are generally defined as a raised ridge just below where the mane ends.' Does a centaur in fact HAVE withers? Instead of an area over the front legs, the tail usually flicks the flanks, the thighs -more or less- on the hind legs. Also, direct address is set off with commas(or a comma and another punctuation mark; or a comma and the start of a sentence): 'You could use a little more tact, Vanore!' (also, 'Of course, it's the sites on their side.' further down.

Regarding the barrier -you can't have holes in one side of a wall. Either the barrier holds or it fails, but it doesn't fail on one side and not the other. ((Unless it gives onto another destination? Does it?))