Battle of Rishi was released as part of the Shadow of Revan expansion (patch 3.0) in December 2014. Blood Hunt and Battle of Rishi were part of the expansion's main storyline and the first two flashpoints that launched with a solo mode right off the bat. Group-wise they only offered a tactical version initially, with the hardmode getting added in 3.1 two months later. At the time of writing this, more than a year later, Blood Hunt and Battle of Rishi are still the two newest flashpoints in the game, as no additional ones have been released. (Personally I don't think that the Star Fortresses really count, since they can't seem to decide what sort of content they want to be and aren't included in the group finder.)
Battle of Rishi is a romp across Rishi to take out a massive Revanite signal jammer, so you spend your time fighting Revanites and their droids. The trash is pretty uninteresting, and the bosses... well, they offer some reasonably interesting mechanics but are pretty darn forgettable in terms of story.
The first two boss encounters each feature a Revanite duo consisting of a former Republic and a former Imperial character, first a Wookiee (smuggler?) and an Imperial soldier, then a Sith and a Jedi master. There's a lot of "don't stand in squares/circles on the floor" in both fights, but the second encounter features an interesting mechanic where balls of lightning float towards the middle of the room and you have to "soak them up" or they'll do more damage to the whole group. Like in many duo fights, killing one of the bosses first results in the other enraging, both in the first and in the second encounter. Now, stuff like that sometimes gets announced in big red letters across the screen that say something like: "[Boss name] gets really angry!" In both of these boss fights though, no matter whom you kill first, the same line is used for all of them: "The remaining adversary rages at the death of their ally!" It's like not even the encounter designers could be bothered. "Who cares? Nobody has heard of these guys before and nobody will ever hear from them again after they're dead. They have no personality, no story and no lines. Why bother?"
Exhibits A and B.
To give credit where credit is due, at least the last boss - a walker that conveniently drops from the sky (yes, really) - is quite memorable, at least mechanically. It has this move where it powers up a massive electric discharge... which will one-shot you even in tactical mode. To survive, you have to go stand in a circle and use a console to activate a protective shield around you and any allies. There is plenty of time to do this, so it's not a matter of reflexes or anything, just a question of paying some attention to your environment. Yet the amount of people I've watched die to this... it's always pretty hilarious. I also have my own funny memories of this encounter, such as that one time when our entire group went to stand in the circle like good little players, but then nobody actually bothered to click on the console so we all died anyway, looking very foolish in the process.
On hardmode, there is also a bonus boss, who is probably the most mechanically challenging flashpoint boss I've ever seen in this game - which is quite impressive really! I talked about him a bit in this post. Unfortunately the sheer difficulty of the fight also makes him unappealing to anyone but a well-geared, fully organised group. I think he's cool in theory, but in nearly a year I've only actually bothered to kill him twice myself, which is kind of telling.
Battle of Rishi is directly integrated into the Shadow of Revan story, so it's hard to talk about it without giving at least minor spoilers for that... the major plot point is that you're fighting Revanites, and both a Republic and an Imperial fleet have just appeared above the planet, manipulated by the Revanites to hopefully annihilate each other. In order to prevent this, you need to contact your faction's representative, but a local signal jammer makes communication with the fleet impossible. So you charter a shuttle and invade yet another Revanite camp to destroy said signal jammer.
The entire flashpoint is just you fighting your way towards your objective, with a brief light/dark side choice near the end where you get to hijack an anti-air cannon and can decide to aim it either at the Revanites or at the enemy faction.
Once the signal jammer has been destroyed, you get in touch with your respective faction's leader in orbit (Satele Shan for Republic players and Darth Marr for Imperials) and they agree to temporarily halt aggressions to figure out what's going on.
I think most of my articles in this series have been pretty positive so far, but Battle of Rishi is not a flashpoint that impressed me. It features pretty environments, and it offers a fun little mob-killing romp for a pug, but other than that... it just seems to have no heart and no real point.
About a year ago, I wrote a post called Solo Flashpoints - Good or Bad Idea? in which I kind of came to the concusion that Bioware doesn't really seem to know what it wants to do with flashpoints. To be honest, I suspect that's part of why we haven't seen any in a year, not just because of KotFE! In the past, they've sometimes been story-light instances for group content, or an excuse to provide a particularly epic final boss battle. Battle of Rishi doesn't really try to do either, as it came with a solo mode from the get-go and is tightly integrated into the storyline, yet the objective of "go destroy that signal jammer" is so dull that it could simply have been a regular quest.
It's particularly interesting to compare Battle of Rishi to its partial namesake Battle of Ilum, which also suffered from having a somewhat lacklustre objective... but all throughout, it still told a story, of how Malgus' new Empire included lots of aliens, of the kinds of characters he had managed to win for his cause. Battle of Rishi is one massive wasted opportunity here, with the Revanites theoretically boasting an interesting background that has inspired both Republic and Imperial soldiers to defect... yet nothing is made of this whatsoever. None of the people you fight ever go beyond being random mooks, and in a game that prides itself in its lore and interesting characters as much as SWTOR, that's just outright shameful.