Crystalians are a cool boss, at least in terms of their innards. Although their AIs are relatively simple, they've still got some interesting stuff going on, and they have a few unique properties that fit together in interesting ways.
Let's look at the most complex of the three, the Ringblade AI. This is the first AI numerically, and the other two seem to have leftover unused code blocks from it, so I think it's safe to assume that this was created first and the others were added as variants of it. (I think the Staff might actually be a variant of the Spear as well, for that matter.)
What's most interesting here are the attacks it does when you're prone or guard-broken. It's not visible on this chart, but Ringblade Crystalian will also typically use Shove when you have your shield up. These together make it probably the single boss that is most reactive to the player's state of anything I've seen so far—more even than Margit! A complex interplay between what the player does and what a boss does is the thing I love most about my favorite FromSoft game, Sekiro, so I'd love to see them go further down this path.
It's particularly fascinating to me that it has an entire attack, Chakram Swing, which it only ever uses when the player's guard is broken. I've seen that before, but usually only with moves that are clearly finishers; this is just a normal-looking move. What's more, it's the only move of the Ringblade Crystalian's that's parryable, which has injected into my heart the perverse desire to do a parry-only fight in which I intentionally let it break my guard so I can parry its follow-up move.
The other two aren't as complex or interesting in their own right as the Ringblade, although the Spear Crystalian does also pay attention to when you're blocking. Instead of diving into them in particular, I want to talk about the mechanical thing that makes Crystalians unique: their "cracking" system.
For those who haven't played Elden Ring, here's how it works from a player's perspective. When you first start a fight with a Crystalian, it will have very high hardness (so most weapons will bounce off it) and very high defense (so most attacks will do very little damage). But when you deal enough "stance damage"—a hidden damage type that builds up until enemies fall to their knees and become vulnerable to a critical hit—to break their stance, they suddenly start staggering from every hit and taking tons of damage. It's a clever little puzzle that makes the bosses a breeze once you figure it out.
I looked into how this worked internally. As with so many things, it's based on a speffectid: 11550, to be precise. All Crystalians are configured to spawn in with this set. Unlike many of the other speffectids we've talked about which have no meaning in and of themselves and are only used as arbitrary flags to control AI or events, 11550 intrinsically grants the Crystalians their hardness and massive damage reduction. But it's also assigned to an spcategory, 100, which means that any other speffectid in the same category will override it.
You may see where this is going. There's another speffectid, 11551, which is also in spcategory 100 but confers no benefits. The Crystalian's "stance break" animation 8700, sets speffectid 11551 which overrides 11550 and removes its superpowers.
8700Every time I dive into these behaviors, I'm impressed by their parsimony: so little of what I would consider intrinsic parts of a boss's identity actually needs to be written as executable code. Almost everything is represented as this network of spreadsheets, 3D models, and piano rolls, and while the connections between them can at times be difficult to follow or even outright messy there's an undeniable beauty to how well it all fits together in the end to make a coherent and functional whole.