while you perform hit-and run-style strafing attacks
It's not like they can make the battle as simple as smashing Yhorm to pieces using Storm Ruler, but having Radahn's massive attacks focused on someone else while you perform hit-and run-style strafing attacks to Elden Ring Runes your horse's own is much better than having him on your ass the whole time. Even better, in the event that your allies die - and trust me, they'll die frequently--you'll be able to summon them over and over. It's the law.
It's true that you can summon Patches into the Radahn fight too, but don't expect him to stick there.
In any case, the fireworks truly happen in the event that Radahn is defeated. Similar to what Sellen claimed, his death means that the stars can again move. They must be looking for a stretch however, as they begin flying through the heavens in masse, filling the sky with luminous light as they return to their normal cycles. As soon as a comet is swept towards the ground and crashes on the horizon, opening a massive chasm in Mistwood an early-game area. This remains a permanent geophysical feature for the duration of your gameplay and gives players to enter a brand new area called Nokron which is also known as the Eternal City.
It's true that the process of defeating Souls bosses will often change the world around you, I can't recall anything of this magnitude that was happening in previous games.
Although Elden Ring has its fair share of bugs, that is part of the normal course. Development is difficult even in the best of times. Given recent troubles in the last several years it's almost a marvel that FromSoftware was able to release an ambitiously huge game that is still running pretty well for most people. (It's certainly no Cyberpunk 2077). Keep calm and keep away from this portion of cheap Elden Ring Items the game for now.
