One complaint that you might hear from your Cleric players is that there are not enough Celestials for them to summon. The
Ki-Rin is sadly way too powerful to really help in that regard, but it is an interesting addition to the game anyway.
The art in Volo’s for the Ki-Rin is pretty odd. It’s very eye-catching, and dominates the page that it is on (thanks to lots of white space and the shiny colours) but it doesn’t impress all that much. It’s okay, don’t get me wrong, but just not my favourite by a long shot.
The Ki-Rin gets one of the longest entries in the book, at two pages, and it fills a lot of that space with a description of how they fit into the world. I know that other things in the game - Kenku, Oni, etc - are Asian themed monsters, but the Ki-Rin feels the least well integrated of any of them. Perhaps because the name is the most obviously foreign of the three? Either way, I’m not that big a fan of it. They operate as something like a cross between a Unicorn (horned horse protector of a place with magical powers) and an Angel (flying messenger spirit of a god). I’m a big fan of the Unicorn, having used them from time to time and found them a really useful NPC to be able to draw up, and the Ki-Rin being a bigger flying version isn’t really justifying itself to me. I suppose that you could have some fun stuff with the players interacting with the ‘forces of heaven’ in their plane, so Unicorns, Angels
and Ki-Rin, and then probably it will stand out nicely from the other two, but when needing a symbol of Good's involvement in the fight, I think that I’d find myself reaching for a Deva every time.
They have a tendency to gather followers and use their lairs as shrines and monastic retreats. That is probably a nice place for a Hermit to have discovered his Secret, or for an Acolyte to have learned his religion, letting you use this as an in-built NPC that the players can seek out at their own pace.
This is one of the things that you’re not really meant to fight. Regardless, it has a boss profile, with
Legendary Resistance, 18th-level Cleric spellcasting that focuses on healing not harming, three attacks a turn for decent if underwhelming damage, and Legendary Actions. I think that this profile is designed to fight
alongside the players, healing them and not overshadowing them in the damage department. If you wanted to hurt players, then having it just fly overhead and cast
Sacred Flame from maximum range is probably about as good as it’ll get.