A phantom controlled by π (pi), a former member of the Board who was previously in charge of Yggdrasil's promotional affairs. It can utilize the illusory realm to move and attack.

pi (π) is the boss of the special chapter “Realm of Illusion.” She blatantly favours using Siris - Ksana, and is seemingly designed to make fighting her extremely unfun and ineffective if you choose to use anyone else. Let’s just get this over with.

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Attacks and Behaviour

During the fight, pi will periodically become invulnerable, teleport, or both.

As well, multiple circular zones will regularly spawn in random locations around the map.

Entering the center of the zone will provide you with a damage buff, so it’s definitely worth it to keep your eyes out for nearby spawns and take advantage of this. That is, unless you’re playing Siris, in which case you get to ignore that because you’re already perfectly suited to fighting pi even without those buffs!

DigiStorm Wave

pi shoves a wave of energy forward that knocks you back on hit. This attack is quite fast and requires decent reflexes to dodge in time. Or if you play Siris, you can just charge right through it with your standard skill, because it makes you immune to the knockback.

At higher difficulty levels, she’ll also summon homing projectiles after the shove, but those are pretty easy to avoid, even if you got hit by the initial attack.

DigiSleet Barrage

pi fires projectiles down around the map as well as firing them outward in rings on the ground. That’s really it. It’s a freebie. At higher difficulty levels, she’ll also fire homing projectiles at you, but I’ve already gone over how (un)threatening those are.

Mindflux Beam

pi summons four lasers on the ground and spins in place, rotating the lasers with her. Getting hit by the lasers will stagger you. The frequency of the laser hits make this actually pretty annoying to deal with unless you commit to dodging or jumping over all of them, or you have some other source of CC resistance. Fortunately, Siris does have that when she’s using her standard skill, so you can also completely ignore this attack if you’re using her.

Negative Charge DigiWeb

pi teleports to the far end of the map (she will always do this) and summons an electric fence that moves towards you. Being hit by it will stagger you. You can break the little ball things to create gaps in the fence, but it’s really not worth the effort. Make sure to adjust your aim once she teleports back to specifically not waste shots hitting those, as one will initially spawn right between you and her head. Of course, you can also just completely ignore this and charge right up to her with Siris’ standard skill anyways.

Total Recall

When pi has 1/3 of her health remaining, she will turn invulnerable and spawn two rotating lasers on either side of the arena. These basically work like the ones from her Mindflux Beam attack.

Now, you might have noticed that pi has four balls orbiting around her. Wonder what those are for? I’m so glad you asked. Well you see, each ball that’s still alive by the end of pi’s HP trigger will restore her health, restoring HP all the way back to full health if you don’t destroy any of them.

Oh, and did I mention that it’s a hard HP gate, which means you can’t even skip it? That means you’re forced to sit through the invulnerability phase, and you’re forced to break the balls if you don’t want to kill her from full HP again, then sit through *another* hard HP gated trigger. Thankfully, pi consumes the balls to heal herself, so she can only heal herself once.

At higher difficulty levels, the balls have quite a lot of HP, and enough ricochet rate to even bounce sniper shots pretty regularly. As well, they count as part of pi and not as separate enemies. This means that Cherno - Enigma can’t stack Enmity on them, and neither can she damage them by detonating her orbs. How are you supposed to efficiently take them out?  Now you won’t believe this, but Siris’ standard skill deals damage to up to five enemies in front of her, which just happens to be enough for you to damage all four balls and pi herself.

Strategy

Use Siris.

pi is a pretty straightforward fight aside from the fact that she teleports a lot and has that stupid ball minigame. She also does a surprising amount of damage, and is one of very few bosses where I actually had to be careful about not dying. Most of the strategy will depend on which DPS you use, so the only general advice I can really give here is to take advantage of the buff circles whenever possible and make sure to break her balls before she finishes her HP trigger.

Did I mention that you should just use Siris - Ksana?

Wallhacks (Real) (Not Clickbait)

You can jump onto the wall at the side of the arena, which will let you avoid all of pi's actually threatening attacks. You can't collect buff circles here though, so only consider this if you're struggling to clear pi at all. It is kind of an exploit though, so don't be surprised if it gets patched out at some point.

Team Building

pi is seemingly designed to very blatantly favour Siris - Ksana as a DPS choice, to a degree that’s quite frankly disgusting. Other DPS picks, even pretty invested ones, will struggle to get anywhere near the times that an entry-level Siris can put out. The main reason for this is the hard gated HP trigger, and by extension the floating balls around pi. Breaking the balls is vital to a fast (or less slow) run, because the last thing you want is to essentially restart the fight all over again. And it’s the fact that you have to break the balls along with other factors that gate almost every other DPS from viability:

• Cherno - Enigma can’t stack Enmity on the balls, and they also don’t take damage from her orb pops. I guess Seasun was too worried that she would outperform Siris and hurt sales.
• Fritia - Hush can actually deal with the balls decently enough, but gets screwed over by pi potentially teleporting out of range of her ult, as well as the extended HP trigger invulnerability.
• Haha, Coronet. Good one.
• 40% Kinetic resistance means that both Marian - Swift and Haru - Absconditus are out of action, which is really a shame because Haru might have been good here, or at least as a tech option to specifically delete the balls. Swift also would have the mobility to collect the buff circles when they spawn, but we apparently can’t have nice things.
• Oh, you thought having Thermal vulnerability means that Yao - Winter Solstice would be good here? Man, do I wish that was true. Keep in mind that the balls have enough ricochet rate to affect sniper shots, and that they’re just really tanky. In my own testing, they were able to survive two shots from Yao WHILE she was in her ultimate. There’s simply no way to efficiently break the balls with her.

This leaves us with three “viable” DPS options. Lyfe - Wild Hunt can split DPS between pi and the balls thanks to her standard skill, though her overall damage will still be lacking. Another option is Katya - Blue Bolt, who can swap to AoE mode and deal damage to the balls with the splash damage from hitting pi. However, you do suffer the caveats that using AoE mode comes with, like reduced fire rate and a higher S-Energy cost to sustain her skill which leads to reduced skill uptime and lower DPS. Finally, Chenxing - Ethereal Cloud can lock onto the orbs with her standard skill to simultaneously deal damage to the balls while shooting pi. Despite that, you still cut it pretty close unless you specifically shoot the balls, and missing even one of the balls with a skill cast can ruin your entire run.

So yeah, just use Siris, the DPS operative released along with pi. Her standard skill is perfect for doing damage to pi and the balls at the same time, and this also gives her U-Energy to use her ultimate, which very conveniently stops time so you can freely charge it up on pi.

For supports, you can consider bringing sources of Paralyze and Slow to reduce the pressure a bit, as pi is vulnerable to those. Mauxir - Shadow Ka loses a lot of value due to pi’s frequent invulns and the fact that you also have to break the balls (you can’t target them with Mauxir’s support skill, or else that would have been a neat strategy). Enya - Exuvia has at least okay synergy with the four usable DPS operatives, and her support skill area will also immune you to pi’s CC shenanigans. Other than that, the generic damage buffers will also do fine. As stated before, pi does hurt a surprising amount, so bring a healer if you need it.